My stylesheet:

html>body #container
{ 
  width: 690px;
  margin: auto;
  padding: 0;
}

#container
{
  margin: 0 auto; 
  text-align: left;
  height: 100%;
  border: 0;
  voice-family: "\"}\""; 
  voice-family: inherit;
  width: 690px;
  margin: 0 0 0 46px;
}

Here's what is going on: the #container definition is parsed by IE and contains a special "IE only" margin setting of a 46 pixel left margin. It is only applied to IE because Internet Explorer doesn't recognize the "html>body #container" selector and thus ignores it. However, Firefox, Safari etc DO recognize "html>body #container" because they actually comply with the CSS standard. Now because "html>body #container" is more specific selector than "#container" its rules take precedence over any other styles defined in less specific classes. Thus, Firefox and Safari effectively ignore the 46px margin (technically they override the 46px margin with a zero pixel margin).

And that's that.

That didn't make any sense did it?