+1  A: 

give the div (nice rime) overflow:hidden

Itay Moav
+3  A: 

Add the following CSS formatting to the container div:

overflow: auto;

Also, it seems that you need to specify a width for the container div if you want the solution to work correctly in Opera and IE for Windows.

See http://www.quirksmode.org/css/clearing.html for more information.

Steve

Steve Harrison
Your solution requires adding a div with clear:both.....
Itay Moav
According to the Quirksmode page I have linked to, adding a div with "clear: both" is the old solution. The newer one is to add "overflow: auto" and "width: 100%" to the container div.
Steve Harrison
In that case, you see the problem with width:100%, it might change the entire layout. Why not the simple overflow: hidden; ?
Itay Moav
Right, I see the problem with "width: 100%"—I've modified my answer accordingly.
Steve Harrison