Shameless plug to my favorite toolkit: Qt has had this for ages now: <a href="http://doc.qt.nokia.com/4.6/stylesheet.html" rel="nofollow">http://doc.qt.nokia.com/4.6/stylesheet.html</a><p>The Qt guys also have been trying to take this a step further with the declarative UI / QML (basically a tiny DSL for UIs) project:<p><a href="http://labs.trolltech.com/blogs/2009/05/13/qt-declarative-ui/" rel="nofollow">http://labs.trolltech.com/blogs/2009/05/13/qt-declarative-ui...</a>
Great in concept, but copying from CSS itself seems like a bad idea. The lack of abstraction can lead to some really inelegant stylesheets or necessitate writing the stylesheet in another language and generating CSS with a compiler. The lack of conditionals and variables is, to my way of thinking the most significant limitation.
. . . and still look horrible.<p>You can't say that here! But the screenshot makes it pretty clear.<p>Edit: that's the default engine, as it says in the blog post. I still think GTK looks awful, but this is not really good evidence.