2 browser compatibilty issues

1.) I’m using an <iframe> element… and i need the vertical scrollbar, but for some weird reason firefox also adds a horizontal bar… how on earth to get rid of that ? I tried googling it, but got no ideas.

2.) my css looks like this:


html, body {
 margin-left: 4px;
 margin-top: 4px;
 margin-right: 4px;
 margin-bottom: 4px;
}

the problem is that it displays a correct 4px margin in IE6, but a 6px margin in FireFox 1.5.0.4… why is it larger in firefox and how to lose the 2 extra pixels ?