Change CSS rule at runtime

Question

How do I change any CSS properties during runtime?
Suppose I have:

#mycss {
   background:#000;
   padding:0;
}

Then during runtime,

Answer 1

You can't really change the css other than switching to a whole new stylesheet or overwriting it. Wat may be the easiest method is this: (JavaScript)

document.getElementById('idOfObject').backgroundColor = "#fff";

See also this page for a similar problem: http://www.kirupa.com/html5/changing_css_using_javascript.htm