Showing posts with label web maintenance. Show all posts
Showing posts with label web maintenance. Show all posts
Friday, 14 September 2012
Thursday, 13 September 2012
CSS3 (Cascading Style Sheets)
Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation semantics (the look and formatting) of a document written in a markup language. Its most common application is to style web pages written in HTML and XHTML, but the language can also be applied to any kind of XML document, including plain XML, SVG and XUL.
CSS is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation, including elements such as the layout, colors, and fonts.[1] This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple pages to share formatting, and reduce complexity and repetition in the structural content (such as by allowing for tableless web design). CSS can also allow the same markup page to be presented in different styles for different rendering methods, such as on-screen, in print, by voice (when read out by a speech-based browser or screen reader) and on Braille-based, tactile devices. It can also be used to allow the web page to display differently depending on the screen size or device on which it is being viewed. While the author of a document typically links that document to a CSS style sheet, readers can use a different style sheet, perhaps one on their own computer, to override the one the author has specified.
CSS specifies a priority scheme to determine which style rules apply if more than one rule matches against a particular element. In this so-called cascade, priorities or weights are calculated and assigned to rules, so that the results are predictable.
The CSS specifications are maintained by the World Wide Web Consortium (W3C). Internet media type (MIME type) text/css is registered for use with CSS by RFC 2318 (March 1998), and they also operate a free CSS validation service.[2]Contents [hide]
1 Syntax
1.1 Use
1.2 Sources
2 History
2.1 Difficulty with adoption
2.2 Variations
2.2.1 CSS 1
2.2.2 CSS 2
2.2.3 CSS 2.1
2.2.4 CSS 3
2.2.5 CSS 4
3 Browser support
4 Limitations
5 Advantages
6 CSS frameworks
7 Positioning
7.1 Position: top, bottom, left, and right
7.2 Float and clear
8 See also
9 References
10 Further reading
11 External links
[edit]
Syntax
CSS has a simple syntax and uses a number of English keywords to specify the names of various style properties.
A style sheet consists of a list of rules. Each rule or rule-set consists of one or more selectors, and a declaration block. A declaration-block consists of a list of declarations in braces. Each declaration itself consists of a property, a colon (:), and a value. If there are multiple declarations in a block, a semi-colon (;) must be inserted to separate each declaration.[3]
In CSS, selectors are used to declare which part of the markup a style applies to, a kind of match expression. Selectors may apply to all elements of a specific type, to elements specified by attribute, or to elements depending on how they are placed relative to, or nested within, others in the document tree.
Pseudo-classes are used in CSS selectors to permit formatting based on information that is outside the document tree. An often-used example of a pseudo-class is :hover, which identifies content only when the user 'points to' the visible element, usually by holding the mouse cursor over it. It is appended to a selector as in a:hover or #elementid:hover. A pseudo-class classifies document elements, such as :link or :visited, whereas a pseudo-element makes a selection that may consist of partial elements, such as :first-line or :first-letter.[4]
Selectors may be combined in many ways, especially in CSS 2.1, to achieve great specificity and flexibility.[5]
Here is an example using the above rules:
selector [, selector2, ...] [:pseudo-class] {
property: value;
[property2: value2;
...]
}
/* comment */
[edit]
Use
Prior to CSS, nearly all of the presentational attributes of HTML documents were contained within the HTML markup; all font colors, background styles, element alignments, borders and sizes had to be explicitly described, often repeatedly, within the HTML. CSS allows authors to move much of that information to another file, the style sheet, resulting in considerably simpler HTML.
Headings (h1 elements), sub-headings (h2), sub-sub-headings (h3), etc., are defined structurally using HTML. In print and on the screen, choice of font, size, color and emphasis for these elements is presentational.
Prior to CSS, document authors who wanted to assign such typographic characteristics to, say, all h2 headings had to repeat HTML presentational markup for each occurrence of that heading type. This made documents more complex, larger, and more difficult to maintain. CSS allows the separation of presentation from structure. CSS can define color, font, text alignment, size, borders, spacing, layout and many other typographic characteristics, and can do so independently for on-screen and printed views. CSS also defines non-visual styles such as the speed and emphasis with which text is read out by aural text readers. The W3C has now deprecated the use of all presentational HTML markup.[citation needed]
CSS files can be associated with HTML documents using the following syntax:
<link rel="stylesheet" href="http://example.com/css/style.css" type="text/css" />
[edit]
Sources
CSS information can be provided from various sources. CSS style information can be in a separate document or it can be embedded into an HTML document. Multiple style sheets can be imported. Different styles can be applied depending on the output device being used; for example, the screen version can be quite different from the printed version, so that authors can tailor the presentation appropriately for each medium.
Priority scheme for CSS sources (from highest to lowest priority):
Author styles (provided by the web page author), in the form of:
Inline styles, inside the HTML document, style information on a single element, specified using the style attribute
Embedded style, blocks of CSS information inside the HTML itself
External style sheets, i.e., a separate CSS file referenced from the document
User style:
A local CSS file the user specifies with a browser option, which acts as an override applied to all documents
User agent style
Default styles applied by the user agent, i.e., the browser's default settings for each element's presentation
The style sheet with the highest priority controls the content display. Declarations not set in the highest priority source are passed on to a source of lower priority, such as the user agent style. This process is called cascading.
One of the goals of CSS is also to allow users greater control over presentation. Someone who finds red italic headings difficult to read may apply a different style sheet. Depending on the browser and the web site, a user may choose from various style sheets provided by the designers, or may remove all added styles and view the site using the browser's default styling, or may override just the red italic heading style without altering other attributes.
[edit]
History
Håkon Wium Lie, chief technical officer of the Opera Software company and co-creator of the CSS web standard
Style sheets have existed in one form or another since the beginnings of SGML in the 1980s. Cascading Style Sheets were developed as a means for creating a consistent approach to providing style information for web documents.
As HTML grew, it came to encompass a wider variety of stylistic capabilities to meet the demands of web developers. This evolution gave the designer more control over site appearance, at the cost of more complex HTML. Variations in web browser implementations, such as ViolaWWW and WorldWideWeb,[6] made consistent site appearance difficult, and users had less control over how web content was displayed. Robert Cailliau wanted to separate the structure from the presentation.[6] The ideal way would be to give the user different options and transferring three different kinds of style sheets: one for printing, one for the presentation on the screen and one for the editor feature.[6]
To improve web presentation capabilities, nine different style sheet languages were proposed to the World Wide Web Consortium's (W3C) www-style mailing list. Of the nine proposals, two were chosen as the foundation for what became CSS: Cascading HTML Style Sheets (CHSS) and Stream-based Style Sheet Proposal (SSP). CHSS, a language that has some resemblance to today's CSS, was proposed by Håkon Wium Lie in October 1994. Bert Bos was working on a browser called Argo, which used its own style sheet language called SSP.[7] Lie and Yves Lafon joined Dave Raggett to expand the Arena browser for supporting CSS as a testbed application for the W3C.[8][9][10] Lie and Bos worked together to develop the CSS standard (the 'H' was removed from the name because these style sheets could also be applied to other markup languages besides HTML).[11]
Unlike existing style languages like DSSSL and FOSI, CSS allowed a document's style to be influenced by multiple style sheets. One style sheet could inherit or "cascade" from another, permitting a mixture of stylistic preferences controlled equally by the site designer and user.
Lie's proposal was presented at the "Mosaic and the Web" conference (later called WWW2) in Chicago, Illinois in 1994, and again with Bert Bos in 1995.[11] Around this time the W3C was already being established, and took an interest in the development of CSS. It organized a workshop toward that end chaired by Steven Pemberton. This resulted in W3C adding work on CSS to the deliverables of the HTML editorial review board (ERB). Lie and Bos were the primary technical staff on this aspect of the project, with additional members, including Thomas Reardon of Microsoft, participating as well. In August 1996 Netscape Communication Corporation presented an alternative style sheet language called JavaScript Style Sheets (JSSS).[11] The spec was never finished and is deprecated.[12] By the end of 1996, CSS was ready to become official, and the CSS level 1 Recommendation was published in December.
Development of HTML, CSS, and the DOM had all been taking place in one group, the HTML Editorial Review Board (ERB). Early in 1997, the ERB was split into three working groups: HTML Working group, chaired by Dan Connolly of W3C; DOM Working group, chaired by Lauren Wood of SoftQuad; and CSS Working group, chaired by Chris Lilley of W3C.
The CSS Working Group began tackling issues that had not been addressed with CSS level 1, resulting in the creation of CSS level 2 on November 4, 1997. It was published as a W3C Recommendation on May 12, 1998. CSS level 3, which was started in 1998, is still under development as of 2009.
In 2005 the CSS Working Groups decided to enforce the requirements for standards more strictly. This meant that already published standards like CSS 2.1, CSS 3 Selectors and CSS 3 Text were pulled back from Candidate Recommendation to Working Draft level.
[edit]
Difficulty with adoption
The CSS 1 specification was completed in 1996. Microsoft's Internet Explorer 3[11] was released in that year, featuring some limited support for CSS. But it was more than three years before any web browser achieved near-full implementation of the specification. Internet Explorer 5.0 for the Macintosh, shipped in March 2000, was the first browser to have full (better than 99 percent) CSS 1 support,[13] surpassing Opera, which had been the leader since its introduction of CSS support 15 months earlier. Other browsers followed soon afterwards, and many of them additionally implemented parts of CSS 2. As of August 2010, no (finished) browser has fully implemented CSS 2, with implementation levels varying (see Comparison of layout engines (CSS)).
Even though early browsers such as Internet Explorer 3[11] and 4, and Netscape 4.x had support for CSS, it was typically incomplete and had serious bugs. This was a serious obstacle for the adoption of CSS.
When later 'version 5' browsers began to offer a fairly full implementation of CSS, they were still incorrect in certain areas and were fraught with inconsistencies, bugs and other quirks. The proliferation of such CSS-related inconsistencies and even the variation in feature support has made it difficult for designers to achieve a consistent appearance across browsers and platforms. Some authors resorted to workarounds such as CSS hacks and CSS filters.
Problems with browsers' patchy adoption of CSS, along with errata in the original specification, led the W3C to revise the CSS 2 standard into CSS 2.1, which moved nearer to a working snapshot of current CSS support in HTML browsers. Some CSS 2 properties that no browser successfully implemented were dropped, and in a few cases, defined behaviors were changed to bring the standard into line with the predominant existing implementations. CSS 2.1 became a Candidate Recommendation on February 25, 2004, but CSS 2.1 was pulled back to Working Draft status on June 13, 2005,[14] and only returned to Candidate Recommendation status on July 19, 2007.[15]
In the past, some web servers were configured to serve all documents with the filename extension .css[16] as mime type application/x-pointplus[17] rather than text/css. At the time, the Net-Scene company was selling PointPlus Maker to convert PowerPoint files into Compact Slide Show files (using a .css extension).[18]
[edit]
Variations
CSS has various levels and profiles. Each level of CSS builds upon the last, typically adding new features and typically denoted as CSS 1, CSS 2, CSS 3, and CSS 4. Profiles are typically a subset of one or more levels of CSS built for a particular device or user interface. Currently there are profiles for mobile devices, printers, and television sets. Profiles should not be confused with media types, which were added in CSS 2.
[edit]
CSS 1
The first CSS specification to become an official W3C Recommendation is CSS level 1, published in December 1996.[19] Among its capabilities are support for
Font properties such as typeface and emphasis
Color of text, backgrounds, and other elements
Text attributes such as spacing between words, letters, and lines of text
Alignment of text, images, tables and other elements
Margin, border, padding, and positioning for most elements
Unique identification and generic classification of groups of attributes
The W3C no longer maintains the CSS 1 Recommendation.[20]
[edit]
CSS 2
CSS level 2 specification was developed by the W3C and published as a recommendation in May 1998. A superset of CSS 1, CSS 2 includes a number of new capabilities like absolute, relative, and fixed positioning of elements and z-index, the concept of media types, support for aural style sheets and bidirectional text, and new font properties such as shadows.
The W3C no longer maintains the CSS 2 recommendation.[21]
[edit]
CSS 2.1
CSS level 2 revision 1, often referred to as "CSS 2.1", fixes errors in CSS 2, removes poorly supported or not fully interoperable features and adds already-implemented browser extensions to the specification. In order to comply with the W3C Process for standardizing technical specifications, CSS 2.1 went back and forth between Working Draft status and Candidate Recommendation status for many years. CSS 2.1 first became a Candidate Recommendation on February 25, 2004, but it was reverted to a Working Draft on June 13, 2005 for further review. It returned to Candidate Recommendation on 19 July 2007 and then updated twice in 2009. However, since changes and clarifications were made, it again went back to Last Call Working Draft on 7 December 2010.
CSS 2.1 went to Proposed Recommendation on 12 April 2011.[22] After being reviewed by the W3C Advisory Committee, it was finally published as a W3C Recommendation on 7 June 2011.[23]
[edit]
CSS 3
"CSS3" redirects here. For airport code CSS3, see Montréal/Les Cèdres Airport.
Unlike CSS 2, which is a large single specification defining various features, CSS 3 is divided into several separate documents called "modules". Each module adds new capabilities or extends features defined in CSS 2, over preserving backward compatibility. Work on CSS level 3 started around the time of publication of the original CSS 2 recommendation. The earliest CSS 3 drafts were published in June 1999.[24]
Due to the modularization, different modules have different stability and statuses.[25] As of June 2012, there are over fifty CSS modules published from the CSS Working Group.,[24] and four of these have been published as formal recommendations:
2012-06-19 : Media Queries
2011-09-29 : Namespaces
2011-09-29 : Selectors Level 3
2011-06-07 : Color
Some modules (including Backgrounds and Borders and Multi-column Layout among others) have Candidate Recommendation (CR) status and are considered moderately stable. At CR stage, implementations are advised to drop vendor prefixes.[26]
CSS 3 also supports adding round edges to elements via the border-radius property. Increasingly more websites are utilizing this technique for aesthetic purposes.
[edit]
CSS 4
W3C started drafting CSS 4 on September 29, 2009.[27][28] However, it is currently not supported by any major web browser.
One of the new proposed selectors is :matches(). For which
:matches(div, p, nav) span{
font-size: 18px;
}
is the same as:
div span, p span, nav span{
font-size: 18px;
}
Although Gecko and WebKit already have similar functions:[29]
/* Gecko */
-moz-any(div, p, nav) span{
font-size: 18px;
}
/* Webkit */
-webkit-any(div, p, nav) span{
font-size: 18px;
}
Another interesting and especially very usable way are reference combinators. Those allow you to select elements that are referenced by ID by another element, like a form element. The attendant label reference is the "for attribute". You can define a reference combinator by the attribute with forward slashes (/). In case of an input element you wanted to style different (from grey to blue) when you hover its label, you could use the selector label:hover /for/ input.[30]
label:hover /for/ input {
border-color:blue;
}
[edit]
Browser support
Further information: Comparison of layout engines (Cascading Style Sheets)
Because not all browsers correctly parse CSS code, developed coding techniques known as CSS hacks can either filter specific browsers or target specific browsers (generally both are known as CSS filters). The former can be defined as CSS filtering hacks and the latter can be defined as CSS targeting hacks. Both can be used to hide or show parts of the CSS to different browsers. This is achieved either by exploiting CSS-handling quirks or bugs in the browser, or by taking advantage of lack of support for parts of the CSS specifications.[31] Using CSS filters, some designers have gone as far as delivering different CSS to certain browsers to ensure designs render as expected. Because very early web browsers were either completely incapable of handling CSS, or rendered CSS very poorly, designers today often routinely use CSS filters that completely prevent these browsers from accessing any of the CSS. Internet Explorer support for CSS began with IE 3.0 and increased progressively with each version. By 2008, the first Beta of Internet Explorer 8 offered support for CSS 2.1 in its best web standards mode.
An example of a well-known CSS browser bug is the Internet Explorer box model bug, where box widths are interpreted incorrectly in several versions of the browser, resulting in blocks that are too narrow when viewed in Internet Explorer, but correct in standards-compliant browsers. The bug can be avoided in Internet Explorer 6 by using the correct doctype in (X)HTML documents. CSS hacks and CSS filters are used to compensate for bugs such as this, just one of hundreds of CSS bugs that have been documented in various versions of Netscape, Mozilla Firefox, Opera, and Internet Explorer (including Internet Explorer 7).[32][33]
Even when the availability of CSS-capable browsers made CSS a viable technology, the adoption of CSS was still held back by designers' struggles with browsers' incorrect CSS implementation and patchy CSS support. Even today, these problems continue to make the business of CSS design more complex and costly than it was intended to be, and cross-browser testing remains a necessity. Other reasons for the continuing non-adoption of CSS are: its perceived complexity, authors' lack of familiarity with CSS syntax and required techniques, poor support from authoring tools, the risks posed by inconsistency between browsers and the increased costs of testing.
Currently there is strong competition between Mozilla's Gecko layout engine used in Firefox, the WebKit layout engine used in Apple Safari and Google Chrome, the similar KHTML engine used in KDE's Konqueror browser, and Opera's Presto layout engine—each of them is leading in different aspects of CSS.[clarification needed examples would be useful] As of August 2009, Internet Explorer 8, Firefox 2 and 3 have reasonably complete levels of implementation of CSS 2.1.[34]
[edit]
Limitations
Some noted limitations of the current capabilities of CSS include:
Poor controls for flexible layouts
While new additions to CSS 3 provide a stronger, more robust feature-set for layout, CSS is still at heart a styling language (for fonts, colours, borders and other decoration), not a layout language (for blocks with positions, sizes, margins, and so on). These limitations mean that creating fluid layouts generally requires hand-coding of CSS, and has held back the development of a standards-based WYSIWYG editor.[citation needed]
Selectors are unable to ascend
CSS offers no way to select a parent or ancestor of an element that satisfies certain criteria.[35] A more advanced selector scheme (such as XPath) would enable more sophisticated style sheets. However, the major reasons for the CSS Working Group rejecting proposals for parent selectors are related to browser performance and incremental rendering issues.[36]
Vertical control limitations
While horizontal placement of elements is generally easy to control, vertical placement is frequently unintuitive, convoluted, or outright impossible. Simple tasks, such as centering an element vertically or getting a footer to be placed no higher than bottom of viewport, either require complicated and unintuitive style rules, or simple but widely unsupported rules.[35]
Absence of expressions
There is currently no ability to specify property values as simple expressions (such as margin-left: 10% – 3em + 4px;). This would be useful in a variety of cases, such as calculating the size of columns subject to a constraint on the sum of all columns. However, a working draft with a calc() value to address this limitation has been published by the CSS WG.[37] Internet Explorer versions 5 to 7 support a proprietary expression() statement,[38] with similar functionality. This proprietary expression() statement is no longer supported from Internet Explorer 8 onwards, except in compatibility modes. This decision was taken for "standards compliance, browser performance, and security reasons".[38]
Lack of column declaration
While possible in current CSS 3 (using the column-count module),[39] layouts with multiple columns can be complex to implement in CSS 2.1. With CSS 2.1, the process is often done using floating elements, which are often rendered differently by different browsers, different computer screen shapes, and different screen ratios set on standard monitors.
Cannot explicitly declare new scope independently of position
Scoping rules for properties such as z-index look for the closest parent element with a position:absolute or position:relative attribute. This odd coupling has undesired effects. For example, it is impossible to avoid declaring a new scope when one is forced to adjust an element's position, preventing one from using the desired scope of a parent element.
Pseudo-class dynamic behavior not controllable
CSS implements pseudo-classes that allow a degree of user feedback by conditional application of alternate styles. One CSS pseudo-class, ":hover", is dynamic (equivalent of JavaScript "onmouseover") and has potential for abuse (e.g., implementing cursor-proximity popups),[40] but CSS has no ability for a client to disable it (no "disable"-like property) or limit its effects (no "nochange"-like values for each property).
Cannot name rules
There is no way to name a CSS rule, which would allow (for example) client-side scripts to refer to the rule even if its selector changes.
Cannot include styles from a rule into another rule
CSS styles often must be duplicated in several rules to achieve a desired effect, causing additional maintenance and requiring more thorough testing.
Cannot target specific text without altering markup
Besides the :first-letter pseudo-element, one cannot target specific ranges of text without needing to utilize place-holder elements.
[edit]
Advantages
Separation of content from presentation
CSS facilitates publication of content in multiple presentation formats based on nominal parameters. Nominal parameters include explicit user preferences, different web browsers, the type of device being used to view the content (a desktop computer or mobile Internet device), the geographic location of the user and many other variables.
Site-wide consistency
Main articles: Separation of presentation and content and Style sheet (web development)
When CSS is used effectively, in terms of inheritance and "cascading," a global style sheet can be used to affect and style elements site-wide. If the situation arises that the styling of the elements should need to be changed or adjusted, these changes can be made by editing rules in the global style sheet. Before CSS, this sort of maintenance was more difficult, expensive and time-consuming.
Bandwidth
A stylesheet, internal or external, will specify the style once for a range of HTML elements selected by class, type or relationship to others. This is much more efficient than repeating style information inline for each occurrence of the element. An external stylesheet is usually stored in the browser cache, and can therefore be used on multiple pages without being reloaded, further reducing data transfer over a network.
Page reformatting
Main article: Progressive enhancement
With a simple change of one line, a different style sheet can be used for the same page. This has advantages for accessibility, as well as providing the ability to tailor a page or site to different target devices. Furthermore, devices not able to understand the styling still display the content.
Accessibility
Without CSS, web designers must typically lay out their pages with techniques that hinder accessibility for vision-impaired users, like HTML tables (see Tableless web design#Accessibility).
[edit]
CSS frameworks
CSS frameworks are pre-prepared libraries that are meant to allow for easier, more standards-compliant styling of web pages using the Cascading Style Sheets language. Layout-grid-related CSS frameworks include Blueprint, 960 grid, and YUI CSS grids. Like programming and scripting language libraries, CSS frameworks are usually incorporated as external .css sheets referenced in the HTML <head>. They provide a number of ready-made options for designing and laying out the web page. While many of these frameworks have been published, some authors use them mostly for rapid prototyping, or for learning from, and prefer to 'handcraft' CSS that is appropriate to each published site without the design, maintenance and download overhead of having many unused features in the site's styling.[41]
[edit]
Positioning
CSS 2.1 defines three positioning schemes:
Normal flow
Inline items are laid out in the same way as the letters in words in text, one after the other across the available space until there is no more room, then starting a new line below. Block items stack vertically, like paragraphs and like the items in a bulleted list. Normal flow also includes relative positioning of block or inline items, and run-in boxes.
Floats
A floated item is taken out of the normal flow and shifted to the left or right as far as possible in the space available. Other content then flows alongside the floated item.
Absolute positioning
An absolutely positioned item has no place in, and no effect on, the normal flow of other items. It occupies its assigned position in its container independently of other items.[42]
[edit]
Position: top, bottom, left, and right
There are four possible values of the position property. If an item is positioned in any way other than static, then the further properties top, bottom, left, and right are used to specify offsets and positions.
Static
The default value places the item in the normal flow
Relative
The item is placed in the normal flow, and then shifted or offset from that position. Subsequent flow items are laid out as if the item had not been moved.
Absolute
Specifies absolute positioning. The element is positioned in relation to its nearest non-static ancestor.
Fixed
The item is absolutely positioned in a fixed position on the screen even as the rest of the document is scrolled[42]
[edit]
Float and clear
The float property may have one of three values. Absolutely positioned or fixed items cannot be floated. Other elements normally flow around floated items, unless they are prevented from doing so by their clear property.
left
Floats to the left of the line that it would have appeared in; other items may flow around its right side
right
Floats to the right of the line that it would have appeared in; other items may flow around its left side
clear
Forces the element to appear underneath ('clear') floated elements to the left (clear:left), right (clear:right) or both sides (clear:both)
CSS is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation, including elements such as the layout, colors, and fonts.[1] This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple pages to share formatting, and reduce complexity and repetition in the structural content (such as by allowing for tableless web design). CSS can also allow the same markup page to be presented in different styles for different rendering methods, such as on-screen, in print, by voice (when read out by a speech-based browser or screen reader) and on Braille-based, tactile devices. It can also be used to allow the web page to display differently depending on the screen size or device on which it is being viewed. While the author of a document typically links that document to a CSS style sheet, readers can use a different style sheet, perhaps one on their own computer, to override the one the author has specified.
CSS specifies a priority scheme to determine which style rules apply if more than one rule matches against a particular element. In this so-called cascade, priorities or weights are calculated and assigned to rules, so that the results are predictable.
The CSS specifications are maintained by the World Wide Web Consortium (W3C). Internet media type (MIME type) text/css is registered for use with CSS by RFC 2318 (March 1998), and they also operate a free CSS validation service.[2]Contents [hide]
1 Syntax
1.1 Use
1.2 Sources
2 History
2.1 Difficulty with adoption
2.2 Variations
2.2.1 CSS 1
2.2.2 CSS 2
2.2.3 CSS 2.1
2.2.4 CSS 3
2.2.5 CSS 4
3 Browser support
4 Limitations
5 Advantages
6 CSS frameworks
7 Positioning
7.1 Position: top, bottom, left, and right
7.2 Float and clear
8 See also
9 References
10 Further reading
11 External links
[edit]
Syntax
CSS has a simple syntax and uses a number of English keywords to specify the names of various style properties.
A style sheet consists of a list of rules. Each rule or rule-set consists of one or more selectors, and a declaration block. A declaration-block consists of a list of declarations in braces. Each declaration itself consists of a property, a colon (:), and a value. If there are multiple declarations in a block, a semi-colon (;) must be inserted to separate each declaration.[3]
In CSS, selectors are used to declare which part of the markup a style applies to, a kind of match expression. Selectors may apply to all elements of a specific type, to elements specified by attribute, or to elements depending on how they are placed relative to, or nested within, others in the document tree.
Pseudo-classes are used in CSS selectors to permit formatting based on information that is outside the document tree. An often-used example of a pseudo-class is :hover, which identifies content only when the user 'points to' the visible element, usually by holding the mouse cursor over it. It is appended to a selector as in a:hover or #elementid:hover. A pseudo-class classifies document elements, such as :link or :visited, whereas a pseudo-element makes a selection that may consist of partial elements, such as :first-line or :first-letter.[4]
Selectors may be combined in many ways, especially in CSS 2.1, to achieve great specificity and flexibility.[5]
Here is an example using the above rules:
selector [, selector2, ...] [:pseudo-class] {
property: value;
[property2: value2;
...]
}
/* comment */
[edit]
Use
Prior to CSS, nearly all of the presentational attributes of HTML documents were contained within the HTML markup; all font colors, background styles, element alignments, borders and sizes had to be explicitly described, often repeatedly, within the HTML. CSS allows authors to move much of that information to another file, the style sheet, resulting in considerably simpler HTML.
Headings (h1 elements), sub-headings (h2), sub-sub-headings (h3), etc., are defined structurally using HTML. In print and on the screen, choice of font, size, color and emphasis for these elements is presentational.
Prior to CSS, document authors who wanted to assign such typographic characteristics to, say, all h2 headings had to repeat HTML presentational markup for each occurrence of that heading type. This made documents more complex, larger, and more difficult to maintain. CSS allows the separation of presentation from structure. CSS can define color, font, text alignment, size, borders, spacing, layout and many other typographic characteristics, and can do so independently for on-screen and printed views. CSS also defines non-visual styles such as the speed and emphasis with which text is read out by aural text readers. The W3C has now deprecated the use of all presentational HTML markup.[citation needed]
CSS files can be associated with HTML documents using the following syntax:
<link rel="stylesheet" href="http://example.com/css/style.css" type="text/css" />
[edit]
Sources
CSS information can be provided from various sources. CSS style information can be in a separate document or it can be embedded into an HTML document. Multiple style sheets can be imported. Different styles can be applied depending on the output device being used; for example, the screen version can be quite different from the printed version, so that authors can tailor the presentation appropriately for each medium.
Priority scheme for CSS sources (from highest to lowest priority):
Author styles (provided by the web page author), in the form of:
Inline styles, inside the HTML document, style information on a single element, specified using the style attribute
Embedded style, blocks of CSS information inside the HTML itself
External style sheets, i.e., a separate CSS file referenced from the document
User style:
A local CSS file the user specifies with a browser option, which acts as an override applied to all documents
User agent style
Default styles applied by the user agent, i.e., the browser's default settings for each element's presentation
The style sheet with the highest priority controls the content display. Declarations not set in the highest priority source are passed on to a source of lower priority, such as the user agent style. This process is called cascading.
One of the goals of CSS is also to allow users greater control over presentation. Someone who finds red italic headings difficult to read may apply a different style sheet. Depending on the browser and the web site, a user may choose from various style sheets provided by the designers, or may remove all added styles and view the site using the browser's default styling, or may override just the red italic heading style without altering other attributes.
[edit]
History
Håkon Wium Lie, chief technical officer of the Opera Software company and co-creator of the CSS web standard
Style sheets have existed in one form or another since the beginnings of SGML in the 1980s. Cascading Style Sheets were developed as a means for creating a consistent approach to providing style information for web documents.
As HTML grew, it came to encompass a wider variety of stylistic capabilities to meet the demands of web developers. This evolution gave the designer more control over site appearance, at the cost of more complex HTML. Variations in web browser implementations, such as ViolaWWW and WorldWideWeb,[6] made consistent site appearance difficult, and users had less control over how web content was displayed. Robert Cailliau wanted to separate the structure from the presentation.[6] The ideal way would be to give the user different options and transferring three different kinds of style sheets: one for printing, one for the presentation on the screen and one for the editor feature.[6]
To improve web presentation capabilities, nine different style sheet languages were proposed to the World Wide Web Consortium's (W3C) www-style mailing list. Of the nine proposals, two were chosen as the foundation for what became CSS: Cascading HTML Style Sheets (CHSS) and Stream-based Style Sheet Proposal (SSP). CHSS, a language that has some resemblance to today's CSS, was proposed by Håkon Wium Lie in October 1994. Bert Bos was working on a browser called Argo, which used its own style sheet language called SSP.[7] Lie and Yves Lafon joined Dave Raggett to expand the Arena browser for supporting CSS as a testbed application for the W3C.[8][9][10] Lie and Bos worked together to develop the CSS standard (the 'H' was removed from the name because these style sheets could also be applied to other markup languages besides HTML).[11]
Unlike existing style languages like DSSSL and FOSI, CSS allowed a document's style to be influenced by multiple style sheets. One style sheet could inherit or "cascade" from another, permitting a mixture of stylistic preferences controlled equally by the site designer and user.
Lie's proposal was presented at the "Mosaic and the Web" conference (later called WWW2) in Chicago, Illinois in 1994, and again with Bert Bos in 1995.[11] Around this time the W3C was already being established, and took an interest in the development of CSS. It organized a workshop toward that end chaired by Steven Pemberton. This resulted in W3C adding work on CSS to the deliverables of the HTML editorial review board (ERB). Lie and Bos were the primary technical staff on this aspect of the project, with additional members, including Thomas Reardon of Microsoft, participating as well. In August 1996 Netscape Communication Corporation presented an alternative style sheet language called JavaScript Style Sheets (JSSS).[11] The spec was never finished and is deprecated.[12] By the end of 1996, CSS was ready to become official, and the CSS level 1 Recommendation was published in December.
Development of HTML, CSS, and the DOM had all been taking place in one group, the HTML Editorial Review Board (ERB). Early in 1997, the ERB was split into three working groups: HTML Working group, chaired by Dan Connolly of W3C; DOM Working group, chaired by Lauren Wood of SoftQuad; and CSS Working group, chaired by Chris Lilley of W3C.
The CSS Working Group began tackling issues that had not been addressed with CSS level 1, resulting in the creation of CSS level 2 on November 4, 1997. It was published as a W3C Recommendation on May 12, 1998. CSS level 3, which was started in 1998, is still under development as of 2009.
In 2005 the CSS Working Groups decided to enforce the requirements for standards more strictly. This meant that already published standards like CSS 2.1, CSS 3 Selectors and CSS 3 Text were pulled back from Candidate Recommendation to Working Draft level.
[edit]
Difficulty with adoption
The CSS 1 specification was completed in 1996. Microsoft's Internet Explorer 3[11] was released in that year, featuring some limited support for CSS. But it was more than three years before any web browser achieved near-full implementation of the specification. Internet Explorer 5.0 for the Macintosh, shipped in March 2000, was the first browser to have full (better than 99 percent) CSS 1 support,[13] surpassing Opera, which had been the leader since its introduction of CSS support 15 months earlier. Other browsers followed soon afterwards, and many of them additionally implemented parts of CSS 2. As of August 2010, no (finished) browser has fully implemented CSS 2, with implementation levels varying (see Comparison of layout engines (CSS)).
Even though early browsers such as Internet Explorer 3[11] and 4, and Netscape 4.x had support for CSS, it was typically incomplete and had serious bugs. This was a serious obstacle for the adoption of CSS.
When later 'version 5' browsers began to offer a fairly full implementation of CSS, they were still incorrect in certain areas and were fraught with inconsistencies, bugs and other quirks. The proliferation of such CSS-related inconsistencies and even the variation in feature support has made it difficult for designers to achieve a consistent appearance across browsers and platforms. Some authors resorted to workarounds such as CSS hacks and CSS filters.
Problems with browsers' patchy adoption of CSS, along with errata in the original specification, led the W3C to revise the CSS 2 standard into CSS 2.1, which moved nearer to a working snapshot of current CSS support in HTML browsers. Some CSS 2 properties that no browser successfully implemented were dropped, and in a few cases, defined behaviors were changed to bring the standard into line with the predominant existing implementations. CSS 2.1 became a Candidate Recommendation on February 25, 2004, but CSS 2.1 was pulled back to Working Draft status on June 13, 2005,[14] and only returned to Candidate Recommendation status on July 19, 2007.[15]
In the past, some web servers were configured to serve all documents with the filename extension .css[16] as mime type application/x-pointplus[17] rather than text/css. At the time, the Net-Scene company was selling PointPlus Maker to convert PowerPoint files into Compact Slide Show files (using a .css extension).[18]
[edit]
Variations
CSS has various levels and profiles. Each level of CSS builds upon the last, typically adding new features and typically denoted as CSS 1, CSS 2, CSS 3, and CSS 4. Profiles are typically a subset of one or more levels of CSS built for a particular device or user interface. Currently there are profiles for mobile devices, printers, and television sets. Profiles should not be confused with media types, which were added in CSS 2.
[edit]
CSS 1
The first CSS specification to become an official W3C Recommendation is CSS level 1, published in December 1996.[19] Among its capabilities are support for
Font properties such as typeface and emphasis
Color of text, backgrounds, and other elements
Text attributes such as spacing between words, letters, and lines of text
Alignment of text, images, tables and other elements
Margin, border, padding, and positioning for most elements
Unique identification and generic classification of groups of attributes
The W3C no longer maintains the CSS 1 Recommendation.[20]
[edit]
CSS 2
CSS level 2 specification was developed by the W3C and published as a recommendation in May 1998. A superset of CSS 1, CSS 2 includes a number of new capabilities like absolute, relative, and fixed positioning of elements and z-index, the concept of media types, support for aural style sheets and bidirectional text, and new font properties such as shadows.
The W3C no longer maintains the CSS 2 recommendation.[21]
[edit]
CSS 2.1
CSS level 2 revision 1, often referred to as "CSS 2.1", fixes errors in CSS 2, removes poorly supported or not fully interoperable features and adds already-implemented browser extensions to the specification. In order to comply with the W3C Process for standardizing technical specifications, CSS 2.1 went back and forth between Working Draft status and Candidate Recommendation status for many years. CSS 2.1 first became a Candidate Recommendation on February 25, 2004, but it was reverted to a Working Draft on June 13, 2005 for further review. It returned to Candidate Recommendation on 19 July 2007 and then updated twice in 2009. However, since changes and clarifications were made, it again went back to Last Call Working Draft on 7 December 2010.
CSS 2.1 went to Proposed Recommendation on 12 April 2011.[22] After being reviewed by the W3C Advisory Committee, it was finally published as a W3C Recommendation on 7 June 2011.[23]
[edit]
CSS 3
"CSS3" redirects here. For airport code CSS3, see Montréal/Les Cèdres Airport.
Unlike CSS 2, which is a large single specification defining various features, CSS 3 is divided into several separate documents called "modules". Each module adds new capabilities or extends features defined in CSS 2, over preserving backward compatibility. Work on CSS level 3 started around the time of publication of the original CSS 2 recommendation. The earliest CSS 3 drafts were published in June 1999.[24]
Due to the modularization, different modules have different stability and statuses.[25] As of June 2012, there are over fifty CSS modules published from the CSS Working Group.,[24] and four of these have been published as formal recommendations:
2012-06-19 : Media Queries
2011-09-29 : Namespaces
2011-09-29 : Selectors Level 3
2011-06-07 : Color
Some modules (including Backgrounds and Borders and Multi-column Layout among others) have Candidate Recommendation (CR) status and are considered moderately stable. At CR stage, implementations are advised to drop vendor prefixes.[26]
CSS 3 also supports adding round edges to elements via the border-radius property. Increasingly more websites are utilizing this technique for aesthetic purposes.
[edit]
CSS 4
W3C started drafting CSS 4 on September 29, 2009.[27][28] However, it is currently not supported by any major web browser.
One of the new proposed selectors is :matches(). For which
:matches(div, p, nav) span{
font-size: 18px;
}
is the same as:
div span, p span, nav span{
font-size: 18px;
}
Although Gecko and WebKit already have similar functions:[29]
/* Gecko */
-moz-any(div, p, nav) span{
font-size: 18px;
}
/* Webkit */
-webkit-any(div, p, nav) span{
font-size: 18px;
}
Another interesting and especially very usable way are reference combinators. Those allow you to select elements that are referenced by ID by another element, like a form element. The attendant label reference is the "for attribute". You can define a reference combinator by the attribute with forward slashes (/). In case of an input element you wanted to style different (from grey to blue) when you hover its label, you could use the selector label:hover /for/ input.[30]
label:hover /for/ input {
border-color:blue;
}
[edit]
Browser support
Further information: Comparison of layout engines (Cascading Style Sheets)
Because not all browsers correctly parse CSS code, developed coding techniques known as CSS hacks can either filter specific browsers or target specific browsers (generally both are known as CSS filters). The former can be defined as CSS filtering hacks and the latter can be defined as CSS targeting hacks. Both can be used to hide or show parts of the CSS to different browsers. This is achieved either by exploiting CSS-handling quirks or bugs in the browser, or by taking advantage of lack of support for parts of the CSS specifications.[31] Using CSS filters, some designers have gone as far as delivering different CSS to certain browsers to ensure designs render as expected. Because very early web browsers were either completely incapable of handling CSS, or rendered CSS very poorly, designers today often routinely use CSS filters that completely prevent these browsers from accessing any of the CSS. Internet Explorer support for CSS began with IE 3.0 and increased progressively with each version. By 2008, the first Beta of Internet Explorer 8 offered support for CSS 2.1 in its best web standards mode.
An example of a well-known CSS browser bug is the Internet Explorer box model bug, where box widths are interpreted incorrectly in several versions of the browser, resulting in blocks that are too narrow when viewed in Internet Explorer, but correct in standards-compliant browsers. The bug can be avoided in Internet Explorer 6 by using the correct doctype in (X)HTML documents. CSS hacks and CSS filters are used to compensate for bugs such as this, just one of hundreds of CSS bugs that have been documented in various versions of Netscape, Mozilla Firefox, Opera, and Internet Explorer (including Internet Explorer 7).[32][33]
Even when the availability of CSS-capable browsers made CSS a viable technology, the adoption of CSS was still held back by designers' struggles with browsers' incorrect CSS implementation and patchy CSS support. Even today, these problems continue to make the business of CSS design more complex and costly than it was intended to be, and cross-browser testing remains a necessity. Other reasons for the continuing non-adoption of CSS are: its perceived complexity, authors' lack of familiarity with CSS syntax and required techniques, poor support from authoring tools, the risks posed by inconsistency between browsers and the increased costs of testing.
Currently there is strong competition between Mozilla's Gecko layout engine used in Firefox, the WebKit layout engine used in Apple Safari and Google Chrome, the similar KHTML engine used in KDE's Konqueror browser, and Opera's Presto layout engine—each of them is leading in different aspects of CSS.[clarification needed examples would be useful] As of August 2009, Internet Explorer 8, Firefox 2 and 3 have reasonably complete levels of implementation of CSS 2.1.[34]
[edit]
Limitations
Some noted limitations of the current capabilities of CSS include:
Poor controls for flexible layouts
While new additions to CSS 3 provide a stronger, more robust feature-set for layout, CSS is still at heart a styling language (for fonts, colours, borders and other decoration), not a layout language (for blocks with positions, sizes, margins, and so on). These limitations mean that creating fluid layouts generally requires hand-coding of CSS, and has held back the development of a standards-based WYSIWYG editor.[citation needed]
Selectors are unable to ascend
CSS offers no way to select a parent or ancestor of an element that satisfies certain criteria.[35] A more advanced selector scheme (such as XPath) would enable more sophisticated style sheets. However, the major reasons for the CSS Working Group rejecting proposals for parent selectors are related to browser performance and incremental rendering issues.[36]
Vertical control limitations
While horizontal placement of elements is generally easy to control, vertical placement is frequently unintuitive, convoluted, or outright impossible. Simple tasks, such as centering an element vertically or getting a footer to be placed no higher than bottom of viewport, either require complicated and unintuitive style rules, or simple but widely unsupported rules.[35]
Absence of expressions
There is currently no ability to specify property values as simple expressions (such as margin-left: 10% – 3em + 4px;). This would be useful in a variety of cases, such as calculating the size of columns subject to a constraint on the sum of all columns. However, a working draft with a calc() value to address this limitation has been published by the CSS WG.[37] Internet Explorer versions 5 to 7 support a proprietary expression() statement,[38] with similar functionality. This proprietary expression() statement is no longer supported from Internet Explorer 8 onwards, except in compatibility modes. This decision was taken for "standards compliance, browser performance, and security reasons".[38]
Lack of column declaration
While possible in current CSS 3 (using the column-count module),[39] layouts with multiple columns can be complex to implement in CSS 2.1. With CSS 2.1, the process is often done using floating elements, which are often rendered differently by different browsers, different computer screen shapes, and different screen ratios set on standard monitors.
Cannot explicitly declare new scope independently of position
Scoping rules for properties such as z-index look for the closest parent element with a position:absolute or position:relative attribute. This odd coupling has undesired effects. For example, it is impossible to avoid declaring a new scope when one is forced to adjust an element's position, preventing one from using the desired scope of a parent element.
Pseudo-class dynamic behavior not controllable
CSS implements pseudo-classes that allow a degree of user feedback by conditional application of alternate styles. One CSS pseudo-class, ":hover", is dynamic (equivalent of JavaScript "onmouseover") and has potential for abuse (e.g., implementing cursor-proximity popups),[40] but CSS has no ability for a client to disable it (no "disable"-like property) or limit its effects (no "nochange"-like values for each property).
Cannot name rules
There is no way to name a CSS rule, which would allow (for example) client-side scripts to refer to the rule even if its selector changes.
Cannot include styles from a rule into another rule
CSS styles often must be duplicated in several rules to achieve a desired effect, causing additional maintenance and requiring more thorough testing.
Cannot target specific text without altering markup
Besides the :first-letter pseudo-element, one cannot target specific ranges of text without needing to utilize place-holder elements.
[edit]
Advantages
Separation of content from presentation
CSS facilitates publication of content in multiple presentation formats based on nominal parameters. Nominal parameters include explicit user preferences, different web browsers, the type of device being used to view the content (a desktop computer or mobile Internet device), the geographic location of the user and many other variables.
Site-wide consistency
Main articles: Separation of presentation and content and Style sheet (web development)
When CSS is used effectively, in terms of inheritance and "cascading," a global style sheet can be used to affect and style elements site-wide. If the situation arises that the styling of the elements should need to be changed or adjusted, these changes can be made by editing rules in the global style sheet. Before CSS, this sort of maintenance was more difficult, expensive and time-consuming.
Bandwidth
A stylesheet, internal or external, will specify the style once for a range of HTML elements selected by class, type or relationship to others. This is much more efficient than repeating style information inline for each occurrence of the element. An external stylesheet is usually stored in the browser cache, and can therefore be used on multiple pages without being reloaded, further reducing data transfer over a network.
Page reformatting
Main article: Progressive enhancement
With a simple change of one line, a different style sheet can be used for the same page. This has advantages for accessibility, as well as providing the ability to tailor a page or site to different target devices. Furthermore, devices not able to understand the styling still display the content.
Accessibility
Without CSS, web designers must typically lay out their pages with techniques that hinder accessibility for vision-impaired users, like HTML tables (see Tableless web design#Accessibility).
[edit]
CSS frameworks
CSS frameworks are pre-prepared libraries that are meant to allow for easier, more standards-compliant styling of web pages using the Cascading Style Sheets language. Layout-grid-related CSS frameworks include Blueprint, 960 grid, and YUI CSS grids. Like programming and scripting language libraries, CSS frameworks are usually incorporated as external .css sheets referenced in the HTML <head>. They provide a number of ready-made options for designing and laying out the web page. While many of these frameworks have been published, some authors use them mostly for rapid prototyping, or for learning from, and prefer to 'handcraft' CSS that is appropriate to each published site without the design, maintenance and download overhead of having many unused features in the site's styling.[41]
[edit]
Positioning
CSS 2.1 defines three positioning schemes:
Normal flow
Inline items are laid out in the same way as the letters in words in text, one after the other across the available space until there is no more room, then starting a new line below. Block items stack vertically, like paragraphs and like the items in a bulleted list. Normal flow also includes relative positioning of block or inline items, and run-in boxes.
Floats
A floated item is taken out of the normal flow and shifted to the left or right as far as possible in the space available. Other content then flows alongside the floated item.
Absolute positioning
An absolutely positioned item has no place in, and no effect on, the normal flow of other items. It occupies its assigned position in its container independently of other items.[42]
[edit]
Position: top, bottom, left, and right
There are four possible values of the position property. If an item is positioned in any way other than static, then the further properties top, bottom, left, and right are used to specify offsets and positions.
Static
The default value places the item in the normal flow
Relative
The item is placed in the normal flow, and then shifted or offset from that position. Subsequent flow items are laid out as if the item had not been moved.
Absolute
Specifies absolute positioning. The element is positioned in relation to its nearest non-static ancestor.
Fixed
The item is absolutely positioned in a fixed position on the screen even as the rest of the document is scrolled[42]
[edit]
Float and clear
The float property may have one of three values. Absolutely positioned or fixed items cannot be floated. Other elements normally flow around floated items, unless they are prevented from doing so by their clear property.
left
Floats to the left of the line that it would have appeared in; other items may flow around its right side
right
Floats to the right of the line that it would have appeared in; other items may flow around its left side
clear
Forces the element to appear underneath ('clear') floated elements to the left (clear:left), right (clear:right) or both sides (clear:both)
Friday, 31 August 2012
Wordpress
WordPress is a free and open source blogging tool and a dynamic content management system (CMS) based on PHP and MySQL. It has many features including a plug-in architecture and a template system.
WordPress is used by over 16.7% of Alexa Internet's "top 1 million" websites and as of August 2011 manages 22% of all new websites. WordPress is currently the most popular CMS in use on the Internet.
It was first released on May 27, 2003, by founders Matt Mullen and Mike Little as a fork of cafelog. As of December 2011, version 3.0 had been downloaded over 65 million times.
WordPress template hierarchy
WordPress has a web template system using a template processor.
Themes
WordPress users may install and switch between themes. Themes allow users to change the look and functionality of a WordPress website or installation without altering the informational content. Themes may be installed by using the WordPress "Dashboard" administration tool,
or by uploading theme folders via FTP. The PHP and HTML code in themes can also be edited for more advanced customizations.
Plugins
One very popular feature of WordPress is its rich plugin architecture which allows users and developers to extend its abilities beyond the features that are part of the base install; WordPress has a database of over 18,000 plugins with purposes ranging from SEO to adding widgets.
Widgets
Widgets are small modules that offer users drag-and-drop sidebar content placement and implementation of many plugins' extended abilities. Widgets allow WordPress developers to add functionality to their sites. These small modules can be used to add functionality such as a slideshow, Facebook-like box, small news slider, and more.
Multi-user and multi-blogging
Prior to WordPress 3.0, WordPress supported one blog per installation, although multiple concurrent copies may be run from different directories if configured to use separate database tables. WordPress Multi-User (WordPress MU, or just WPMU)
was a fork of WordPress created to allow multiple blogs to exist within one installation that is able to be administered by a centralized maintainer.
WordPress MU makes it possible for those with a website to host their own blogging community, as well as control and moderate all the blogs from a single dashboard. WordPress MU adds eight new data tables for each blog.
WordPress MU merged with WordPress as part of the 3.0 release.
Mobiles
Native applications exist for WebOS, Android, iOS (iPhone, iPod Touch, iPad), Windows Phone 7, and BlackBerry which provide access to some of the features in the WordPress Admin panel and work with WordPress.com and many WordPress.org blogs.
Other features of note
WordPress also features integrated link management; a search engine–friendly, clean permalink structure; the ability to assign nested, multiple categories to articles; and support for tagging of posts and articles. Automatic filters are also included, providing standardized formatting and styling of text in articles (for example, converting regular quotes to smart quotes).
WordPress also supports the Trackback and Pingback standards for displaying links to other sites that have themselves linked to a post or article. One of the best sports blogs on the site is [http://betweenthelineshockeyandbaseball.com
History
cafelog, more commonly known as simply b2 or cafelog, was the precursor to WordPress.
cafelog was estimated[by whom?] to have been employed on approximately 2,000 blogs as of May 2003. It was written in PHP for use with MySQL by Michel Valdrighi,
who is now a contributing developer to WordPress. Although WordPress is the official successor, another project, b2evolution, is also in active development.
WordPress first appeared in 2003 as a joint effort between Matt Mullenweg and Mike Little to create a fork of b2. Christine Selleck Tremoulet, a friend of Mullenweg, suggested the name WordPress.
In 2004 the licensing terms for the competing Movable Type package were changed by Six Apart and many of its most influential users migrated to WordPress.[20][21] By October 2009 the 2009 Open Source content management system Market Share Report reached the conclusion that
WordPress enjoyed the greatest brand strength of any open-source content-management systems.
Awards
In 2007 WordPress won a Packt Open Source CMS Award.
In 2009 WordPress won the Packt best Open Source CMS Awards.
In 2010 WordPress won the Hall of Fame CMS category in the 2010 Open Source Awards.[23]
In 2011 WordPress won the Open Source Web App of the Year Award at The Critters.[24][25]
WordPress is used by over 16.7% of Alexa Internet's "top 1 million" websites and as of August 2011 manages 22% of all new websites. WordPress is currently the most popular CMS in use on the Internet.
It was first released on May 27, 2003, by founders Matt Mullen and Mike Little as a fork of cafelog. As of December 2011, version 3.0 had been downloaded over 65 million times.
WordPress template hierarchy
WordPress has a web template system using a template processor.
Themes
WordPress users may install and switch between themes. Themes allow users to change the look and functionality of a WordPress website or installation without altering the informational content. Themes may be installed by using the WordPress "Dashboard" administration tool,
or by uploading theme folders via FTP. The PHP and HTML code in themes can also be edited for more advanced customizations.
Plugins
One very popular feature of WordPress is its rich plugin architecture which allows users and developers to extend its abilities beyond the features that are part of the base install; WordPress has a database of over 18,000 plugins with purposes ranging from SEO to adding widgets.
Widgets
Widgets are small modules that offer users drag-and-drop sidebar content placement and implementation of many plugins' extended abilities. Widgets allow WordPress developers to add functionality to their sites. These small modules can be used to add functionality such as a slideshow, Facebook-like box, small news slider, and more.
Multi-user and multi-blogging
Prior to WordPress 3.0, WordPress supported one blog per installation, although multiple concurrent copies may be run from different directories if configured to use separate database tables. WordPress Multi-User (WordPress MU, or just WPMU)
was a fork of WordPress created to allow multiple blogs to exist within one installation that is able to be administered by a centralized maintainer.
WordPress MU makes it possible for those with a website to host their own blogging community, as well as control and moderate all the blogs from a single dashboard. WordPress MU adds eight new data tables for each blog.
WordPress MU merged with WordPress as part of the 3.0 release.
Mobiles
Native applications exist for WebOS, Android, iOS (iPhone, iPod Touch, iPad), Windows Phone 7, and BlackBerry which provide access to some of the features in the WordPress Admin panel and work with WordPress.com and many WordPress.org blogs.
Other features of note
WordPress also features integrated link management; a search engine–friendly, clean permalink structure; the ability to assign nested, multiple categories to articles; and support for tagging of posts and articles. Automatic filters are also included, providing standardized formatting and styling of text in articles (for example, converting regular quotes to smart quotes).
WordPress also supports the Trackback and Pingback standards for displaying links to other sites that have themselves linked to a post or article. One of the best sports blogs on the site is [http://betweenthelineshockeyandbaseball.com
History
cafelog, more commonly known as simply b2 or cafelog, was the precursor to WordPress.
cafelog was estimated[by whom?] to have been employed on approximately 2,000 blogs as of May 2003. It was written in PHP for use with MySQL by Michel Valdrighi,
who is now a contributing developer to WordPress. Although WordPress is the official successor, another project, b2evolution, is also in active development.
WordPress first appeared in 2003 as a joint effort between Matt Mullenweg and Mike Little to create a fork of b2. Christine Selleck Tremoulet, a friend of Mullenweg, suggested the name WordPress.
In 2004 the licensing terms for the competing Movable Type package were changed by Six Apart and many of its most influential users migrated to WordPress.[20][21] By October 2009 the 2009 Open Source content management system Market Share Report reached the conclusion that
WordPress enjoyed the greatest brand strength of any open-source content-management systems.
Awards
In 2007 WordPress won a Packt Open Source CMS Award.
In 2009 WordPress won the Packt best Open Source CMS Awards.
In 2010 WordPress won the Hall of Fame CMS category in the 2010 Open Source Awards.[23]
In 2011 WordPress won the Open Source Web App of the Year Award at The Critters.[24][25]
Sunday, 26 August 2012
Joomla
Joomla is a free and open source content management framework (CMF) for publishing content on the World Wide Web and intranets and a model–view–controller (MVC) Web application framework that can also be used independently.
Joomla is written in PHP, uses object-oriented programming (OOP) techniques (since version 1.5[2]) and software design patterns,[3][4] stores data in a MySQL or (since version 2.5) MS SQL database,[5] and includes features such as page caching, RSS feeds, printable versions of pages, news flashes, blogs, polls, search, and support for language internationalization.
As of March 2012, Joomla has been downloaded over 30 million times.[6] Over 10,000 free and commercial extensions are available from the official Joomla! Extension Directory, and more are available from other sources.[7] It is estimated to be the second most used CMS on the Internet after WordPress.[8][9]Contents [hide]
1 History
2 Version history
3 Deployment
4 Examples
5 Joomla templates [40]
5.1 Template Components
5.1.1 Layout
5.1.2 Color Scheme
5.1.3 Images and Effects
5.1.4 Fonts
6 Joomla extensions
7 See also
8 References
9 External links
[edit]
History
Joomla was the result of a fork of Mambo on August 17, 2005. At that time, the Mambo name was trademarked by Miro International Pvt Ltd., who formed a non-profit foundation with the stated purpose of funding the project and protecting it from lawsuits.[10] The Joomla development team claimed that many of the provisions of the foundation structure went against previous agreements made by the elected Mambo Steering Committee, lacked the necessary consultation with key stakeholders and included provisions that violated core open source values.[11]
The Joomla development team created a website called OpenSourceMatters.org to distribute information to users, developers, web designers and the community in general. Project leader Andrew Eddie wrote a letter[12] that appeared on the announcements section of the public forum at mamboserver.com. A little more than one thousand people had joined OpenSourceMatters.org within a day, most posting words of encouragement and support, and the website received the Slashdot effect as a result. Miro CEO Peter Lamont gave a public response to the development team in an article titled "The Mambo Open Source Controversy — 20 Questions With Miro".[13] This event created controversy within the free software community about the definition of "open source". Forums at many other open source projects were active with postings for and against the actions of both sides.
In the two weeks following Eddie's announcement, teams were re-organized, and the community continued to grow. Eben Moglen and the Software Freedom Law Center (SFLC) assisted the Joomla core team beginning in August 2005, as indicated by Moglen's blog entry from that date and a related OSM announcement.[14][15] The SFLC continue to provide legal guidance to the Joomla project.[16]
On August 18, Andrew Eddie called for community input on suggested names for the project. The core team indicated that it would make the final decision for the project name based on community input. The core team eventually chose a name that was not on the list of suggested names provided by the community. On September 22, the new name, "Joomla!," was announced. It is the anglicised spelling of the Swahili word jumla meaning "all together" or "as a whole."[17] On September 26, the development team called for logo submissions from the community and invited the community to vote on the logo; the team announced the community's decision on September 29. On October 2, brand guidelines, a brand manual, and a set of logo resources were published for the community's use.[18]
Joomla won the Packt Publishing Open Source Content Management System Award in 2006, 2007, and 2011.[19][20][21]
On October 27, 2008, PACKT Publishing announced that Johan Janssens was the "Most Valued Person" (MVP), for his work as one of the lead developers of the 1.5 Joomla Framework and Architecture. In 2009 Louis Landry received the "Most Valued Person" award for his role as Joomla architect and development coordinators.
[edit]
Version history
Joomla versionsVersion Release date Supported until
1.0 2005-09-16 2009-07-22
1.5 (LTS) 2008-01-22 2012-12-01
1.6 2011-01-10 2011-08-19
1.7 2011-07-19 2012-02-24
2.5 (LTS) 2012-01-24 2013-12
3.0 2012-09 2013-04
3.1 2013-03 2013-10
3.5 (LTS) 2013-09 2015-06
Release no longer supported
Release still supported
Future release
Joomla 1.0 was released on September 22, 2005 as a re-branded release of Mambo 4.5.2.3 that combined other bug and moderate-level security fixes.
Joomla 1.5 was released on January 22, 2008. The latest release of this version was 1.5.26 on March 27, 2012.[22] This version was the first to attain long term support (LTS). LTS versions are released each three major or minor releases and are supported until three months after the next LTS version is released.[23]
Joomla 1.6 was released on January 10, 2011.[24][25] This version adds a full access control list functionality plus, user-defined category hierarchy, and admin interface improvements.[26]
Joomla 1.7 was released on July 19, 2011, six months after 1.6.0.[27] This version adds enhanced security and improved migration tools.[28]
Joomla 2.5 was released on January 24, 2012,[29] six months after 1.7.0. This version is a long term support (LTS) release. Originally this release was to be 1.8.0, however the developers announced August 9 that they would rename it to fit into a new version number scheme in which every LTS release is an X.5 release.[30][31] This version was the first to run on other databases besides MySQL.
Joomla 3.0 Alpha-1 was released on July 12, 2012, [32] while as Joomla 3.0.0 is due to be released in September 2012.[33] Originally, it was supposed to be released in July 2012; however, the January/July release schedule was uncomfortable for volunteers, and the schedule was changed to September/March releases.[34]
[edit]
Deployment
As with many other popular web applications, Joomla can be run on a LAMP stack.[35]
Many web hosts have control panels that allow for automatic installation of Joomla. On Windows, Joomla can be installed using the Microsoft Web Platform Installer, which automatically detects and installs any missing dependencies, such as PHP or MySQL.[36]
[edit]
Examples
These are some of the websites that use Joomla:
Linux.com[37]
iTWire.com[38]
ComputerNetworkingNotes.com[39]
The official Joomla! site has a directory of example sites: Official Community Showcase
[edit]
Joomla templates [40]
A Joomla template is a multifaceted Joomla extension which is responsible for the layout, design and structure of a Joomla powered website. While the CMS itself manages the content, a template manages the look and feel of the content elements and the overall design of a Joomla driven website. The content and design of a Joomla template is separate and can be edited, changed and deleted separately. The template is where the design of the main layout for a Joomla site is set. This includes where users place different elements (components, modules, and plug-ins), which are responsible for the different types of content. If the template is designed to allow user customization, the user can change the content placement on the site i.e.: putting the main menu on the right or left side of the screen.
[edit]
Template Components
[edit]
Layout
The template is the place where the design of the main layout is set for a Joomla site. This includes where users place different elements (components, modules, and plug-ins), which are responsible for different types of content.
[edit]
Color Scheme
Using CSS within the template design, users can change the colors of the backgrounds, text, links or just about anything that they could using (X)HTML code.
[edit]
Images and Effects
Users can also control the way images are displayed on the page and even create flash-like effects such as drop-down menus.
[edit]
Fonts
The same applies to fonts. The designs for these are all set within the template's CSS file(s) to create a uniform look across the entire site, which makes it amazingly easy to change the whole look just by altering one or two files rather than every single page
[edit]
Joomla extensions
Joomla extension help extend the Joomla websites' ability. There are five types of extensions for Joomla!: Components, Modules, Plugins, Templates, and Languages. Each of these extensions handles a specific function.
Components: Are the largest and most complex extensions of them all; they can be seen as mini-applications. Most components have two parts: a site part and an administrator part. Every time a Joomla page loads, one component is called to render the main page body. Components are the major portion of a page because a component is driven by a menu item and every menu item runs a component.
Plugins: Are more advanced extensions and are, in essence, event handlers. In the execution of any part of Joomla, a module or a component, an event can be triggered. When an event is triggered, plugins that are registered with the application to handle that event execute. For example, a plugin could be used to block user-submitted articles and filter out bad words.
Templates: This describes the main design of the Joomla website and is the extension that allows users to change the look of the site. Users will see modules and components on a template. They are customizable and flexible. Templates determine the “style” of a website.
Modules: Rendering pages flexibly in Joomla requires a module extension, which is then linked to Joomla components to display new content or new images. Joomla modules look like boxes – like the “search” or “login” module. However, they don’t require html to Joomla to work.
Languages: Very simple extensions that can either be used as a core part or as an extension. Language and font information can also be used for PDF or PSD to Joomla conversions.
Saturday, 11 August 2012
Type of Website [Dhanjal Solution]
Responsibilities included:
* Project management
* Preparation of project plans and time estimates
* Flash design and web design
Christmas Site
Real Estate Site
Shopping Cart site
Static website
Dynamic website
School site
News site
personal website
Commercial website
Government website
Basic Website Types
1. Personal Websites
2. Photo Sharing Websites
3. Community Building Websites
4. Mobile Device Websites
5. Blogs
6. Informational Websites
7. Online Business Brochure/Catalog
8. E-commerce Websites
* Project management
* Preparation of project plans and time estimates
* Flash design and web design
Christmas Site
Real Estate Site
Shopping Cart site
Static website
Dynamic website
School site
News site
personal website
Commercial website
Government website
Basic Website Types
1. Personal Websites
2. Photo Sharing Websites
3. Community Building Websites
4. Mobile Device Websites
5. Blogs
6. Informational Websites
7. Online Business Brochure/Catalog
8. E-commerce Websites
Thursday, 19 July 2012
Web Design Company In india
Dhanjal Solution with the base at India is a professional Web Designing/Programing Company. Our Web Designers focus on quality features of Web Design, Email Marketing and Multimedia Presentation. Company confers services such as Logo Designing and Search Engine Optimisation (SEO) in order to enhance the overall look of the Brand.
Friday, 4 May 2012
best website design and development company in the world
Website Designing
Web Design / Custom Web Design, Ecommerce Systems so on and so forth then you certainly have arrived at right place. Dhanjal Solution is a leading effective web design services and other related services in India and all over the world.
Search Engine Optimization (SEO)
The most crucial part of our Internet marketing strategies is professional cost effective search engine optimization. Submitting your site to major Search Engines like Google, Yahoo, Altavista and MSN, we guarantee top listings of your website within months. Remember, SEO is not a one-time process, but a continuous one that has to be rigorously maintained through proper examination and placement of optimized graphics, Meta tags, Alt tags, links, keywords, keyword placement and testing of code.
Web Application Development
Dhanjal Solution has the skills and expertise to build custom software applications and databases as per your unique business needs and requirements.You might want a customer database, an employee pay roll, or want to bring automation and computerization in your business processes. All this requires proper and professional study of your needs and then develop software solutions, which can deliver on those needs.
Internet Marketing
SEM, SMO or Rich Media Planning; we nurture the interactive nature of the Internet to promote your business to the world.
Web Maintenance Services
Dhanjal Solution an offshore Outsourcing Web Development Company India has experienced web developer team who specializes in advanced web application development technologies, eCommerce development solutions, Ajax Programming, custom web application development, Script Installation and Modifications, b2b portal development, b2c portal development, OScommerce web development, asp.net, php web development, php programming, php outsourcing and many other rich web application development services.
Web Hosting
Proud partners of both Indian and US based servers, we provide authoritative and reasonably priced web hosting services with the world’s best.
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