any idea on how to fix this?

[Golgotha]

http://www.search-this.com/cp.html

moz isn't happy

[Shpigford]

don't have a suggestion but it sure doesn't look anything like it does in IE...but you knew that...

[ant1832]

This isn't a 100% solution, but its closer.

      body,html {
        height:               100%;
        margin:               0px 0px;
        padding:              0px 0px;
        width:                100%;
      }

[hurricane.uk]

Mozilla won't render a height beyond what the markup demands using height: X

Try adding:

html>body #elementname { height: auto; min-height: 100%; }

You may need to place them in a container with a pixel set height for the 100% to be meaningful though.