A solution is to make the inner box position absolute
. Something like this:
#TB_ajaxContent {
width: 440px;
overflow-x: hidden;
position: absolute;
top: 30px;
bottom: 10px;
}
This should make the inner div position the way you like it. Here's the updated fiddle - note I've removed height:auto; height:100%
from the inlined style.
This is quite a common trick to get the inner div to 'be as tall as the parent'.