Important and unknown default browser values

Here are some of the default values of your browser
body documentElement
margin unknown or not available unknown or not available
border unknown or not available unknown or not available
padding unknown or not available unknown or not available
overflow unknown or not available unknown or not available
overflow-y (CSS 3) not supported not supported
css width unknown or not available unknown or not available
css height unknown or not available unknown or not available

A complete, helpful and very revealing grid of default values of CSS properties for elements in mainstream browsers is available at Alan Gresley's CSS2.1 User Agent Style Sheet Defaults.

Valid HTML 4.01! CSS compliant Web standards project