Normally when a div tag has to expand to accommodate more content, it does so downwards, adding height onto the bottom of the element rather than the top. For this menu we will want to do the exact opposite – when the user hovers over the thumbnail it should expand upward (think about how the OSX dock works).

We’re going to go about this by making use of position:fixed, which essentially lets us “fix” elements to the bottom. Let’s break down the elements.