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18 February 2014

CSS Limitations and Advantages - DotNet Brother

Limitations of the current capabilities of CSS include:
Selectors are unable to ascend
CSS currently offers no way to select a parent or ancestor of an element that satisfies certain criteria. CSS Selectors Level 4, which is still in Working Draft status, proposes such a selector, but only as part of the “complete” selector profile, not the “fast” profile used in dynamic CSS styling. A more advanced selector scheme (such as XPath) would enable more sophisticated style sheets. The major reasons for the CSS Working Group previously rejecting proposals for parent selectors are related to browser performance and incremental rendering issues.
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.
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. Internet Explorer versions 5 to 7 support a proprietary expression() statement, 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".
Lack of column declaration 
While possible in current CSS 3 (using the column-count module), 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), 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.

Advantages of CSS

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.
A stylesheet, internal or external, specifies 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
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.
Without CSS, web designers must typically lay out their pages with techniques such as HTML tables that hinder accessibility for vision-impaired users 
Site-wide consistency
    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. 

The History of CSS - DotNet Brother

Style sheets have existed in one form or another since the beginnings of Standard Generalized Markup Language (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,[7] 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.[7] 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.[7]
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 HÃ¥kon Wium Lie in October 1994. Bert Bos was working on a browser called Argo, which used its own style sheet language called SSP.[8] Lie and Yves Lafon joined Dave Raggett to expand the Arena browser for supporting CSS as a testbed application for the W3C.[9][10][11] 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).[12]
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 inheritor "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.[12]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).[12] The spec was never finished and is deprecated.[13] 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 2014.
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.