css - 为什么 CSS 接受 'grey' 而不是 'colour' ？

Question

作为主要使用英式英语的人，CSS 不接受 colour 作为有效属性这一事实相当令人讨厌，尤其是当它接受 grey(及其偏差)作为有效值。为什么 CSS 允许在值中使用英式英语，而不是在属性中？

根据W3 CSS color specification ，CSS color 值的官方拼写是gray:

但是，它也接受grey(及其偏差)就好了:

.gray {
  color: gray;
}

.grey {
  color: grey;
}

<span class="gray">gray</span>
<span class="grey">grey</span>

这也是有道理的，因为 X11 color names (其中 CSS 颜色级别 3 adapted from)将 grey 拼写列为有效替代。

但是，为什么 CSS Colors Level 3 不允许将 colour 作为属性？

.color {
  color: red;
}

.colour {
  colour: red;
}

<span class="color">color</span>
<span class="colour">colour</span>

规范的创建者允许替代值而非属性是否有特定原因？

Answer 1

非常有趣的是，这个选择的历史有据可查。

CSS 规范有 this issue其中谈到了这一点。在那里 Tab Atkins(tabatkins) 链接到 this video Alex Sexton 给出的关于 CSS 命名颜色背后的(非常有趣和有趣)历史的 JSConf。

According to Sexton , grey 值最初被添加到麻省理工学院的 rgb.txt指定“X11 颜色”的文件，因为

some programmers at HP couldn't remember which one was right.

几年后，Chris Lilley(svgeesus) 将这些值添加到 SVG 颜色中，最终 CSS3(早在 2001 年)将如 Ian Hickson(Hixie) 所说，

[...] merely to codify current practice. Almost every browser supports them and that isn't going to change (because it would break many sites [...]

现在，这并没有告诉我们为什么我们没有 colour 属性。为此，让我们回到 tabatkins gives a hint 的 CSS 问题。这是一个经常性的请求。同样的 svgeesus 当时确实将命名颜色添加到 SVG 中也是 intervenes in this thread并解释说

The aliasing of international-English grey and US-English gray is least problematic as a property value (but would probably still not be adopted, were those keywords to be proposed today). As a functional notation, it would be more problematic; it would require precedence and de-duplicating rules in case both were specified. Even more so for aliasing the color property to colour (and the same for all the *-color* properties.

Sorry, this would add far more issues than it solves.