Html – Automated testing of CSS and HTML front-end coding

I'm a front-end developer coding CSS, HTML and Javascript (in that order) and most of the work I do is design-lead. Whilst the quality of the designs I create with CSS is subjective, much of the coding is purely functional / layout and I am interested in any way to automate the testing of my page.

My question can be split into two parts

1. Does anyone have any existing
   techniques or suggestions for
   automatically testing CSS or HTML,
   particularly with regard
   cross-browser compatibility?

2. As CSS can be roughly divided
   into properties that control layout
   and those that control design, is
   automated testing only viable for
   layout (it can't be possible to
   automatically and valuably test that
   a colour is correct, for example)? If so, what
   sort of CSS values might be suitable
   for boolean acceptance tests?

Here are my initial examples of boolean layout values that could be tested – there must be others?

• Does a pop-up appear above other content (z-index)
• Does a footer clear all other content (float)

Thanks for your help. Part three of the question is of course "Am I wasting my time going down this route?".

***** edit *****

I have found this article that asks the same questions I've asked, but more in depth and perhaps a little more eloquently.

http://www.morethanseven.net/2008/10/13/unit-testing-css-looking-solution/

Moving forward I am trying to isolate some examples from my work where CSS alone has caused functional errors however those that I've found so far are bugs with JS and CSS combined. I would still like to automatically test these sorts of errors, but appreciate that with javascript used it is beyond the scope of my original question.

***** edit 2 *****

I've since blogged about how I set about solving this problem, available here:

http://blog.ajcw.com/2010/12/automated-css-testing-or-how-one-css-coder-is-now-responsible-for-breaking-%E2%80%93-and-fixing-%E2%80%93-the-build/