css级联样式表

CSS2雄心壮志 (CSS2 ambitions precipitated)

To meet the first specification does not cover even CSS1, CSS is assigned in 1997 to a new working group at W3C, chaired by Chris Lilley. In 2007, this group shall include representatives from Apple, Google, IBM, Microsoft, Adobe, Mozilla Foundation and Opera.

为了满足第一个规范甚至不包括CSS1的要求，CSS于1997年分配给W3C的一个新工作组，由Chris Lilley主持。 在2007年，该小组应包括苹果，谷歌，IBM，微软，Adobe，Mozilla基金会和Opera的代表。

Published as a recommendation in May 1998, the second level of CSS considerably extends the theoretical possibilities of cascading style sheets, especially with about 70 additional properties. At the typographic layout of text in addition initiated with CSS1 end:

作为建议，于1998年5月发布，第二级CSS极大地扩展了级联样式表的理论可能性，尤其是具有大约70个附加属性。 在以CSS1结尾的文本的排版中：

• Declination in styles specific to different media in which a web page can be restored (print, delivered by a speech synthesizer, a Braille device, a projection device, a mobile, etc.).可以恢复网页的不同媒体特有的样式偏斜(打印，由语音合成器，盲文设备，投影设备，移动设备等提供)。
• New positioning properties to the screen to enable the realization of advanced layout, from a document developed jointly by Microsoft and Netscape微软和Netscape共同开发的文档为屏幕提供了新的定位属性，以实现高级布局
• A set of properties allowing the downloading of fonts specific一组允许下载特定字体的属性
• New properties to involve the user preferences in the shaping of a site.涉及用户偏好的新属性，以塑造网站。

However, this feature-rich will only have limited coverage in its implementations:

但是，此功能丰富的实现将仅具有有限的实现范围：

• The declination media is partly a failure: the vocal style renderings are lack of theoretical consideration by voice browsers and screen readers. They are otherwise incompatible with the standard interaction SSML. It is the same display and printing Braille. The print styles are only very partially adopted by the graphical browsers, while some mobile browsers to ignore as the early 2000s the CSS media type that is dedicated to them.磁偏角媒体在某种程度上是一种失败：语音浏览器和屏幕阅读器缺乏人声表达的理论考虑。 它们否则与标准交互SSML不兼容。 它是相同的显示和打印盲文。 图形样式仅部分地被图形浏览器采用，而一些移动浏览器则在2000年代初期忽略了专用于它们CSS媒体类型。
• Only a few advanced positioning properties are recognized by all graphical browsers, thereby consolidating the practical layout based on deflections of CSS features (or floating block system set) and HTML (tables layouts).所有图形浏览器仅识别出一些高级定位属性，从而基于CSS功能(或浮动块系统集)和HTML(表格布局)的变形来合并实际布局。
• The download fonts raises implementations and divergent between Netscape and Internet Explorer, and is opposed by publishers fonts, anxious to protect their business interests.下载字体引起了Netscape和Internet Explorer之间的实现方式和分歧，并且遭到发布者字体的反对，他们渴望保护其商业利益。

Several reasons are cited for these difficulties and slow implementations of CSS2:

列举了CSS2的这些困难和缓慢实施的几个原因：

• “Under-specification ofcertain sections”. Håkon Lie himself stresses in his thesis on cascading style sheets, in 2005, the risk of loss or non-implementation of interoperability relating to “excessive features, such as markers of the list, cutting marks for printing or downloading of fonts. Similarly, the complexity of advanced selectors is difficult to reconcile with the management of the waterfall.“某些部分的规格不足”。 HåkonLie本人在其级联样式表中的论文中强调说，在2005年，与“过多特征(例如列表标记，用于打印或下载字体的裁切标记)有关的丢失或无法实现互操作性的风险”。 同样，高级选择器的复杂性很难与瀑布的管理相协调。
• The lack of interest from manufacturers of browsers for functionality that did not necessarily fit their strategic or commercial objectives.浏览器制造商对不一定符合其战略或商业目标的功能缺乏兴趣。
• Discontinuation of development of the Internet Explorer browser dominating the market, from 2001 to 2006. Håkon Lie Leo wrote in 2005: “2001 was a turning point for CSS. That was the year Microsoft Internet Explorer 6.0 product which provides a support functional, though incomplete and buggy, CSS. No other browser has been able to compete Winie in terms of number of users. Winie has, therefore, determined the subset of CSS used by the authors. The limited support of CSS Winie, combined with a de facto monopoly in web browser, is currently the most serious problem of deployment of CSS.从2001年到2006年，Internet Explorer浏览器在市场上的发展停滞。HåkonLie Leo在2005年写道：“ 2001年是CSS的转折点。 那一年，Microsoft Internet Explorer 6.0产品提供了一种支持功能，尽管功能不完善且有缺陷。 就用户数量而言，没有其他浏览器能够与Winie竞争。 因此，Winie已经确定了作者使用CSS的子集。 CSS Winie的有限支持，加上在网络浏览器中的事实上的垄断，是当前CSS部署中最严重的问题。

CSS 2.1, return to implementations

CSS 2.1，返回实现

Returns implementation of CSS2 lead the working group to draft W3C CSS from 2001 a revised CSS 2.1 (CSS Level 2 Revision 1 “), based on what was actually adopted by different browsers . The objectives of this review are:

基于CSS2的返回实现，工作组根据不同浏览器的实际使用情况，从2001年起草拟了W3C CSS修订版CSS 2.1(CSS Level 2 Revision 1”)。 这次审查的目标是：

• Maintain compatibility with those portions of CSS2 that are widely accepted and implemented.保持与CSS2被广泛接受和实施的部分的兼容性。
• Incorporated in the standard CSS2 errata all previously published.纳入所有先前发布的标准CSS2勘误表中。
• When the implementations are very different from the CSS2 specification, change the specification for it is consistent with generally accepted practices.当实现与CSS2规范有很大不同时，请更改其规范，以与公认的惯例一致。
• Remove CSS2 features which have been rejected by the CSS community, given their lack of implementation. CSS 2.1 aims to reflect the CSS mechanisms have been reasonably widely implemented for HTML and XML in general (rather than a particular XML language, or HTML only).由于缺少实现，请删除CSS社区拒绝CSS2功能。 CSS 2.1旨在反映CSS机制已经普遍合理地广泛应用于HTML和XML(而不是特定的XML语言或仅HTML)。
• •    Remove the mechanisms that will CSS2 obsoleted by CSS3, and thus encourage the adoption of CSS3 mechanisms in place.•删除CSS2将被CSS3淘汰的机制，从而鼓励采用CSS3机制。
• •    Add a (very) small number of new property values, when implementation experience has shown that they were responding to a need for implementing CSS2.•当实施经验表明它们响应了实施CSS2的需求时，添加(很少)新属性值。

CSS2 CSS 2.1 corrects many points of detail, remove some sections in whole or part (vocal styles set the media type in “aural, print styles, downloadable fonts, whose definitions are pushed more evidence the future CSS3), and the explicit findings from updated at implementations (the advanced management of blocks floating through the “formatting contexts”).

CSS2 CSS 2.1纠正了许多细节问题，全部或部分删除了某些部分(声音样式​​将媒体类型设置为“听觉，打印样式，可下载字体，其定义被更多地证明是将来CSS3的证据)，以及从更新中得出的明确结论。在实现中(通过“格式化上下文”浮动的块的高级管理)。

After hitting eight successive drafts, CSS 2.1 is a Candidate Recommendation in July 2007, that is to say the standard to be followed by implementations.

在达到八份连续的草案之后，CSS 2.1成为了2007年7月的候选推荐标准，也就是说，实施将遵循的标准。

In 2007, no browser has indeed completed the integration of CSS 2.1: it would be implemented to 56% from the Internet Explorer 7, Firefox 2 by 91% and 94% by Opera 9 [36]. Moreover, only a portion of graphical browsers have passed or retained as an objective the Acid2 test, launched in 2005 by the Web Standards Project, the initiative Håkon Lie, to promote the implementation of a particular choice of CSS 2.1 features regarded as the main advances needed: positioning of elements in the display, generalization of the model rendering table to all elements, generated content using CSS. The business use of CSS is therefore limited to an arbitrary subset thereof, determined by the common implementations.

在2007年，没有浏览器确实完成了CSS 2.1的集成：Internet Explorer 7，Firefox 2的实现率分别为91％和Opera 9的实现率分别为56％和94％[36]。 此外，只有一部分图形浏览器已经通过或保留了由Web标准项目(HåkonLie)于2005年发起的Acid2测试作为目标，以促进实现某些特定CSS 2.1功能，这些功能被认为是主要的进步。需要：在显示中放置元素，将模型渲染表推广到所有元素，使用CSS生成内容。 因此，CSS的商业用途仅限于由常见实现方式确定的任意子集。

CSS3 (CSS3)

The development of the third level of cascading style sheets began in 1999, alongside that of CSS 2.1.

第三级层叠样式表的开发始于1999年，与CSS 2.1一起进行的。

CSS3 is “modular” to facilitate its updates, but its implementation by user agents, capabilities and needs of increasingly diverse (graphical browsers, mobile browsers, voice browsers). Browsers can then implement subsets of CSS3.

CSS3是“模块化的”，以促进其更新，但是其通过用户代理的实现，功能和需求日益多样化(图形浏览器，移动浏览器，语音浏览器)。 然后，浏览器可以实现CSS3的子集。

Therefore, the degree of progress varies CSS3 modules and the degree of priority given to them by the CSS Working Group [38]. In 2007, the most advanced modules (candidate recommendations) concerning the formatting ruby annotations, negotiating style between servers and user agents (“Media Queries”), rendering Web TV, color management or decision into account the configuration of the user interface.

因此，进展程度会因CSS3模块以及CSS工作组给予它们的优先级而异[38]。 在2007年，有关格式化Ruby注释，服务器与用户代理之间的协商样式(“媒体查询”)，渲染Web TV，颜色管理或决定用户界面配置的最高级模块(候选建议)。

Study: From Wikipedia, the free encyclopedia. The text is available under the Creative Commons.

研究：来自维基百科，免费的百科全书。 该文本可在“ 知识共享”下找到 。

翻译自: https://www.eukhost.com/blog/webhosting/css-cascading-style-sheets-part-3/

css级联样式表