Submenu does not stay open

I have a little problem here with my dropdown menu.

When I hover a link, the submenu slides out but doesn't stay open.

The problem has something to do with my "content" div element, 开发者_开发知识库because when I remove this div it works. But I can't find my error.

Maybe someone can have a look at it. ;-)

Here is the menu.

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It has to do with the fact the #content comes after #navigation and it's z-index is higher. If you set both position: relative and set the z-index of #navigation to a higher value than #content it'll work as you expect. See http://jsfiddle.net/tangibleJ/B4aDM/2/.