It does so for IE6+, FF3+, Chrome 10+ and Safari 4+. It starts out by setting up the display for HTML5 elements for pre-HTML5 browsers, and handles such other inconsistencies as odd text resizing in IE6 and IE7 that occurs when the body font size is set in ems. It even goes so far as to prevent iOS text resizing when the orientation is changed. Even Chrome's idiosyncrasies are dealt with, such as its odd display of the outline around focused anchors.
It does all this and more, in a brief, well documented stylesheet, which its authors, Nicolas Gallagher and Jonathan Neal, intend to be used as a starting point for projects. They humbly suggest that it not be taken wholesale as a "black box", but should be considered fully customizable.