3 vertical divs floating with 1 background, background scrolls with shortest

Well I have 3 div's floating next to eachother. And the 3 divs are in a bigger div with background image. Now are the left and right div 600px in height and that is set and the middle (container) is auto height. But I want the background of the 3 divs always to be the same height as the left and right div dut it only scrolls with the middle div.

Maby I can't explain开发者_StackOverflowe this correct so if you could take a real quick look at the website.

This is when its correct with lots of content: Good

This is the incorrect page... Bad

I'm guessing its not something big and I dont know what coding to post here so to overcome lots and lots of coding here maby this is better if you could take a quick peek.

Thanks!

Add overflow: hidden to the #mainbg div

#mainbg { overflow: hidden; }

try add:

<div style="clear:both;line-height:0"></div>

after the last div.

edit: i don't watch to the source code first so a little bit change...

1. create a new div into mainbg and add all 3 middle part divs in it
2. then you can use clearing div after this one.