I’m sorry but it is beyond the scope of these forums to deal with basic CSS issues. Try a dedicated CSS resource such as http://www.css-discuss.org/ instead. I’d also recommend using Firefox with the Firebug add-on for this kind of CSS work. http://getfirebug.com/
You’ll need to give each divider a colour.
Your Divider “#main” has a white background so I’d start by removing that.
once you have removed that you are going to have to have to give each of the dividers a back ground colour.
as shown in this image
I’d say go with esmi’s answer though and get some help from css-discuss.
I don’t agree with firefox though 😛
Chrome has the inspect element feature built in and it just seems to run much more smoothly for me then firebug.