Your link doesn't work so I'm just giving general advice.
The way to get a div to expand to suit the text inside is not to give it a height; it will expand to suit the content and can then expand more if someone increases text size and if there is room. This won't work all the time, but will if nothing else is stopping the div from expanding down.
If you have a background color or image in the div without a height but with a float, you may have to use special code that drags the background down as floated divs are assumed to have no height, but it seems that this is not your problem.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.