CSS Browser Selector is a very small (811 bytes) JavaScript which empower CSS selectors. It gives you the ability to write specific CSS code for each operating system and each browser that can be merged into your normal classes. The idea came from 37 Signals browser selector idea and Rafael Lima just did it.

This one line JavaScript will greatly help web developers on CSS hacks. Maybe you can now say “Yes” to your customers if ever they asked you: “Will my site looks the same on most browsers?“. Putting aside the troublesome IE6, a very detail-oriented client will still give you headaches on consistent browser rendering. Let’s take for example Firefox 3.0.8 and Opera 9.64. Now create a simple form with radio buttons and checkboxes. When you view it on those browsers, they didn’t look the same. It’s fine in Firefox but in Opera, the labels just move up a little bit. With CSS Browser Selector, you can create a class specific for Opera to fix the line alignment.

Demo & Documentation: http://rafael.adm.br/css_browser_selector/
Download: http://github.com/rafaelp/css_browser_selector/tree/master
License: Creative Commons Attribution 2.5 Generic