Why Do My Left And Right Side Bars Not Expand

Hi all,

I'm putting this simple site together using my limited CSS knowledge!

http://www.enderbyland.com/newsite/

For some reason the left and right side bars don't expand to the height of the middle content area (which I want to be variable).

Can anyone advise as to why?

Thanks in advance...

Regards,

Andy

I've sorted this another way (using a full width background image) so now have a solution.

I'd still be keen to know how it's done 'properly' though :-)

Andy