My #container div sets a 15px margin on the top and bottom. Unfortunately, the bottom margin does not seem to be working unless overflow:hidden is set. [Check the sidebar on the homepage for an example](http://themeforward.com/demo2/ “”).
I can’t set overflow:hidden on #container because the sub-menu will be hidden under the footer on shorter pages. For example at [http://themeforward.com/demo2/?page_id=1846](http://themeforward.com/demo2/?page_id=1846 “”) when I set overflow:hidden on container the sub-menu under ‘Categories’ becomes hidden.
My current CSS
margin: 15px auto
Because you’ve floated your sidebar, the container is only growing to the height of main content. You just need to add a [clearfix](http://css-tricks.com/snippets/css/clear-fix/ “http://css-tricks.com/snippets/css/clear-fix/”) to the container element and the container will grow to the height of the sidebar and the margin-bottom will be applied.
The sidebar is breaking out of the container because it’s not cleared. You’ll need to use a clearfix on the container — setting “overflow:hidden;” on it would be one way but since you can’t use that, you’ll need another way (having said that though, I didn’t see any problems with the submenu even when the container DOES have overflow:hidden;).
Try adding the following code in your CSS and then add a class “clearfix” to your container.