级联样式表

CSS-难以成熟 (CSS — Difficult to maturation)

Unlike software, the CSS specifications are developed by successive versions, which would allow a browser to refer to a particular version. CSS was developed by “levels”, forcing each new level to integrate the preceding, and each implementation to be compatible with the previous one: CSS1 is developed to be a subset of CSS2, which is itself designed to be a subset of CSS3. This partly explains the slow progress of normative CSS.

与软件不同，CSS规范是由连续的版本开发的，这些版本允许浏览器引用特定的版本。 CSS是由“级别”开发的，它迫使每个新级别都集成前一个级别，并且每个实现都必须与前一个级别兼容：CSS1被开发为CSS2的子集，而CSS2本身被设计为CSS3的子集。 这部分解释了规范CSS的进展缓慢。

浏览器大战期间CSS1的实现很困难 (CSS1 implementations difficult during the browser wars )

The final specification is published CSS1 December 17, 1996, and fifty sets of properties. CSS1 defines itself as a “mechanism simple style sheet, allowing authors and readers to attach style (etc.) in HTML documents. This simplicity is reflected in the choice of a language that can be easily read and written directly by its human users, and language consistent with normal practice in publishing computer. The eventual choice to express CSS syntax in XML or SGML, raised regularly to prevent the implementation of a new mode of parsing, is definitely ruled out.

最终规范于1996年12月17日发布于CSS1，并包含50组属性。 CSS1将自身定义为“机制简单的样式表，允许作者和读者在HTML文档中附加样式(等)”。 这种简单性体现在选择一种易于被其人类用户直接读取和编写的语言，以及与出版计算机中的常规做法一致的语言。 绝对排除了为避免使用新的解析模式而定期提出的以XML或SGML表示CSS语法的最终选择。

CSS1 does not describe only its own grammar: the first level in effect describes a grammar designed to allow the subsequent levels add new features, while authorizing the future reading these stylesheets by implementations of origin. These new features will not be understood by implementations of origin, but may be identified as such and ignored. CSS ensures its compatibility.

CSS1不仅描述了它自己的语法：实际上，第一个级别描述的语法旨在允许后续级别添加新功能，同时授权将来通过源实现来阅读这些样式表。 这些新功能不会被原产地实现所理解，但可以这样识别并忽略。 CSS确保其兼容性。

CSS1 essentially defines the typographical rendering properties of text: fonts (fonts), color, font size, fat, padding, border management and markers list. There is therefore no question of “layout” property float, which will be subsequently used extensively for CSS layout designs comprehensive web is then conceived as a way to place locally, coast to coast, a small portion of content, such as an image, and the rest of the text. Given the problematic implementations of CSS1, the diversion of the HTML table for managing the overall layout remains the immediate solution most commonly used by the authors of web content.

CSS1本质上定义了文本的印刷呈现属性：字体(字体)，颜色，字体大小，粗细，填充，边框管理和标记列表。 因此，毫无疑问存在“ layout”属性浮动，该属性随后将广泛用于CSS布局设计，然后构想出全面的Web，将其作为一种本地放置方式，沿海岸到海岸放置一小部分内容(例如图像)，以及其余文字。 考虑到CSS1的实现存在问题，转移HTML表格以管理整体布局仍然是Web内容作者最常使用的直接解决方案。

In 1996, Internet Explorer 3.0 is the first commercial browser to implement CSS in part while it is still being formulated. This early implementation, led by Chris Wilson does not match the final specification. In 1997, Internet Explorer 4.0 saw the birth of a new rendering engine, Trident, causing the problem but growing support for CSS in different versions of the browser on Windows, until IE7 included.

1996年，Internet Explorer 3.0是第一个实现CSS的商业浏览器，部分仍在制定之中。 由Chris Wilson领导的早期实施与最终规范不符。 1997年，Internet Explorer 4.0诞生了一个新的渲染引擎Trident，这引起了问题，但在Windows的不同版本的浏览器中，对CSS的支持越来越多，直到包括IE7。

Netscape Navigator 4.0 follows the movement in 1997, despite its historic reticence vis-à-vis CSS : in the context of the browser wars, then it is mainly to ensure that Microsoft can not assert itself as the browser more compliant. However, this implementation precipitated, based on internal methods javascript, finally proves little readable content producers. Netscape Navigator 4.0 also provides an implementation JSSS, which will remain short-lived. Not until the new Gecko rendering engine and its integration in Netscape 6 for achieving real implementation of CSS1.

尽管Netscape Navigator 4.0相对于CSS具有历史性保留，但它还是跟随1997年的发展而发展：在浏览器大战的背景下，这主要是为了确保Microsoft不能断言自己的浏览器更加兼容。 但是，基于内部方法javascript促成的这种实现最终证明了几乎没有可读的内容生产者。 Netscape Navigator 4.0还提供了一个实现JSSS，它将保持短暂状态。 直到新的Gecko渲染引擎及其在Netscape 6中的集成才能实现CSS1的真正实现。

In 1998, while ending the browser wars between Netscape and Microsoft, Opera 3.5, which is Håkon Lie meanwhile become the technical director, achieves a more complete implementation of CSS1, aided by the publication of the first “Test suite for Cascading Style Sheets (CSS) Level 1 “by Eric Meyer created primarily for the W3C. The presence of these test suites is proving a major asset for both implementations in browsers and ownership of CSS techniques by the authors (by providing detailed examples of properties and their values).

1998年，在结束Netscape和Microsoft之间的浏览器之战的同时，HåkonLie兼任技术总监的Opera 3.5实现了CSS1的更完整实现，并发布了第一个“级联样式表测试套件(CSS)”。 )“第1级”，主要由Eric Meyer为W3C创建。 这些测试套件的存在证明了浏览器实现和CSS技术拥有者的主要资产(通过提供属性及其值的详细示例)。

Finally, spurred on by Tantek Çelik, Internet Explorer 5.0 for Macintosh was launched in March 2000 based on Tasman, a specific renderer unrelated Trident is the first browser to fully support (over 99%) CSS1. For compatibility with previous coding practices specific to each implementation (the “tag soup”) and allow the proper display of Web documents to be respectful or not standard CSS and HTML, it is also the first to implement the technique of doctype switching. Subsequently adopted by all browsers, it subsequently became one of the keys to the phased implementation of CSS: it makes it possible to keep old browser implementations owners for reasons of compatibility, while having the opportunity to opt in, according to the syntax of the type declaration page document, a method to conform to new standards implementations.

最终，在TantekÇelik的刺激下，基于Tasman的Macintosh Internet Explorer 5.0于2000年3月启动，与Trident无关的特定渲染器是第一个完全支持(超过99％)CSS1的浏览器。 为了与特定于每种实现的以前的编码实践(“标签汤”)兼容，并允许Web文档的正确显示不受到标准CSS和HTML的尊重，这也是首次实现doctype切换技术。 随后被所有浏览器采用，随后成为分阶段实现CSS的关键之一：由于兼容的原因，它可以保留旧的浏览器实现所有者，以保持兼容性，同时根据类型的语法有机会选择加入声明页面文档，一种符合新标准实现的方法。

During this period the late 1990s, web design is primarily dependent on the use of HTML as a presentation format. Netscape’s defeat at the end of the browser wars, the renewal that follows through the Mozilla project, the appearance of IE5 Mac, and to a lesser extent the evolution of Windows Internet Explorer 5.x, however, begin in early 2000 a new stage in the evolution of design practices of the websites by the authors: These browsers make it possible to show that the historical practice dating back to the browser wars, mixing structure and presentation, can actually be abandoned in favor of an approach based on style sheets and more general respect for web standards (within the meaning of HTML and CSS). Jeffrey Zeldman, co-founder of the Web Standards Project and founder of A List Apart in 1998, appears as the figurehead of this movement to promote standards. It is also the inspiration for a design approach “hybrid”, taking advantage of CSS techniques while staying temporarily in the context of formatting documents based on presentation boards.

在1990年代后期，网页设计主要依赖于HTML作为表示格式的使用。 Netscape在浏览器大战结束时失败了，随后通过Mozilla项目进行了更新，出现了IE5 Mac，并在较小程度上发展了Windows Internet Explorer 5.x，但在2000年初开始进入新的阶段。作者对网站设计实践的演变：这些浏览器可以显示出可以追溯到浏览器大战，混合结构和表示形式的历史实践，实际上可以放弃使用基于样式表等的方法。对网络标准的一般尊重(HTML和CSS的含义)。 Web标准项目的联合创始人和1998年A List Apart的创始人Jeffrey Zeldman似乎是推动标准运动的代表人物。 这也是设计方法“混合”的灵感，它利用CSS技术同时暂时停留在基于演示板格式化文档的上下文中。

CSS2，雄心壮志 (CSS2, ambitions precipitated )

To meet the first specification does not cover even CSS1, CSS is awarded in 1997 to a new working group within W3C, chaired by Chris Lilley. In 2007, this group included 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年被授予由Chris Lilley主持的W3C内部的一个新工作组。 2007年，该小组的成员来自苹果，谷歌，IBM，微软，Adobe，Mozilla基金会和Opera。

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 CSS1 initiated with particular effect:

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。 另外，在文本的排版中，CSS1开始产生了特殊的效果：

• Declination in styles specific to different media in which a web page can be restored (print, delivered by a voice synthesizer, a Braille device, a projection device, a phone, etc.).
  可以恢复网页的不同媒体所特有的样式偏斜(打印，由语音合成器，盲文设备，投影设备，电话等提供)。
• New positioning properties on the screen to enable the implementation of advanced layout, from a document developed jointly by Microsoft and Netscape
  屏幕上的新定位属性可以实现高级布局，该属性来自Microsoft和Netscape共同开发的文档
• 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 rich functionality not found an echo in his limited implementations:

但是，这种丰富的功能并未在他有限的实现中产生回响：

• The breakdown by media is in part a failure: the vocal style renderings remain theoretical lack of consideration by voice browsers and screen readers. They are otherwise incompatible with the standard interaction SSML. It is the same display and printing Braille. Print styles are only very partially adopted by graphical browsers, while some mobile browsers do not yet know in the early 2000s the CSS media type that is dedicated to them.
  媒体的崩溃在某种程度上是一种失败：声音风格的渲染在理论上仍然缺乏语音浏览器和屏幕阅读器的考虑。 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，而某些移动浏览器在2000年代初期还不知道专用于它们CSS媒体类型。
• Only a few advanced positioning properties are recognized by all graphical browsers, thus 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 met opposition from publishers fonts, anxious to protect their commercial interests.
  下载字体引起了Netscape和Internet Explorer的实现和分歧，并遇到了发布者字体的反对，他们急于保护其商业利益。

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 。

To be continued…

未完待续…

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

级联样式表