CSS3 the pseudo-class :root
Some Examples
div id="normal"
This block should render as gray text on a light gray background on most CSS-aware browsers. No hacks are employed in the CSS rule for this block.
div id="onlyGeckoForNow"
This block on the other hand should display white italicized text against a green background for browsers that recognize the :root pseudo-class. As of May 2005 it seems that only Gecko-based browsers such as Mozilla, Firebird, and Netscape 7 do.
The CSS rules for the above are as follows:
div#normal, div#onlyGeckoForNow { margin: 1em; padding: 1em; background: #eee; } :root div#onlyGeckoForNow { background: #090; color: white; font-style: italic; }