CSS Browser Selector

Clever technique to help you on CSS hacks.
CSS Browser Selector is a very small javascript with just one line and less than 1kb which empower CSS selectors. It gives you the ability to write specific CSS code for each operating system and each browser.
EXAMPLE

http://rafael.adm.br/css_browser_selector/
Source of this example:
<style type=”text/css”>
.ie .example {
background-color: yellow
}
.ie7 .example {
[...]