Why is this in programming?
Anyway, firstly you might be interested in css shorthand:
This:
body {
margin-top: 0px;
margin-right: 0px;
margin-bottom: 0px;
margin-left: 0px;
}
can be this (you don't need a unit for nothing)
body {
margin: 0;
}
An article to explain more:
Introduction to CSS Shorthand
I can't remember the exact code to remove all page margins, but it's something like this:
body {
margin: 0px;
padding: 0px;
}
body, html {height: 100%;}
The 100% page height should cater for Opera, but I don't know about mac browsers.