RE: CSS 中 border-width 为何不支持百分比？

www-style邮件组里有人这么问了，“% is not a valid unit for border-width”。决策者当时觉得没什么需求，而且有些（浏览器）实现有不均bug，就抛弃了。也许以后会加上。看回复有个同学提供了历史会话：
issue #2
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fantasai: percentage border width, issue 26
... any pressing reason to add this?

daniel: is there a use case for this?
fantasai: don't know one
daniel: don't see border width specified this way, rather in pixel; jason?
jason: agree. can't think of a use case where the percentage border width is to be  used.
<dbaron> I would note that one reason you don't see non-pixel borders is that
... some implementations (e.g., older version of Gecko) will often make them uneven,
... which isn't what authors want.

molly: the only place (I can think of) is scalable design; not someone is practicing  these days.
david b: [repeating his comments above]

<fantasai> jason: I don't think it will make or break any designs
daniel: so we can resolve it by not doing this for now
<fantasai> RESOLVED: no percentage bordershttp://lists.w3.org/Archives/Public/www-style/2008Jun/0032.html





From: yiorsi@gmail.com
Date: Fri, 31 May 2013 16:39:14 +0800
To: public-html-ig-zh@w3.org
Subject: CSS 中 border-width 为何不支持百分比？

在 CSS2.1 中可以看到：http://www.w3.org/TR/CSS21/box.html#border-width-properties



'border-top-width', 'border-right-width', 'border-bottom-width', 'border-left-width'
Percentages: N/A