Yahoo! recommends YUI 3. Learn about YUI 3 CSS Reset on YUILibrary.com.
The foundational YUI Reset CSS file creates a level playing field across A-grade browsers and provides a starting point from which you can explicitly declare your intentions. It normalizes the default rendering of all HTML elements, for example it sets margin, padding, and border to 0, font sizes to YUI Font's default, italic and bold styles to normal, and list-style to none.
All YUI 2.x users should review the YUI 2.8.2 security bulletin, which discusses a vulnerability present in YUI 2.4.0-2.8.1.

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