I found this article after realizing that EXT-JS's CSS class really was not what I wanted. There was some problem in the IE's (of course I forget now what it was). I found this guy Patrick Hunlock who writes some awesome code (I would suggest reading the article I linked to, and not stopping there). I like really clean-looking code, sorry Pat; so I cleaned it a bit and minimized it for you all.
Here is the file.
Here is the class api:
var CSS = {
[CSSStylerule] addCSSRule : function([selector]),
[CSSStylerule] getCSSRule : function([selector]),
[boolean] killCSSRule : function([selector])
};
So, when you say:
var pBold = CSS.addCSSRule('p.bold');
pBold will literally be a CSSStyleRule (as the DOM calls it). Furthermore to modify it:
Hunlock has even more examples on his original post; I also will urge you to Go Forth In Style!
pBold.style.fontWeight = 'bold';
pBold.style.fontSize = '115%';