Instead of merely sliding the target element, Slidedown shifts padding or margin of internal elements

[aaronshaf]

You can see this bug using any major browser by clicking one of the navigation elements on the left column of carm.org

[john]

That's correct, slideDown animates the height, vertical padding, and vertical margin of the element. This is intended. If you wish to animate just the height you can do: .animate({ height: "hide" })