internet explorer setting height from bodyclass

Everything seems to be working pretty well in firefox, but i can't get IE6 or 7 (don't have 8 to try) to set the height of the editor according to the css of the BodyClass

my css is
#content {
float:left;
width:410px;
margin-top:16px;
margin-left:25px;
}
#content.edit {
margin:0;
height:700px;
background-color:#eae0d5;
}

content is the BodyId, and edit is the BodyClass

In firefox my editor is 700px long, but in IE it's the usual default little box. If I set the height in #content IE picks it up fine.

IE is picking up the background colour from #content.edit no problem, so why not the height???

Is there anything i can do, or should i just work round it?