Centering a div horizontally inside a container which can change dimensions

Question

I need to center a div ('#expand') in a container. The div may overlap the content in the container, but only the visible part (i.e. no margins left or right from the div overlapping the content) This example seems to work (using another container and margins on auto), but I need it to overlap the border of the container.

Answer 1

I'm unsure about what you're looking for, exactly, but if you're looking to center an element, you would typically do this:

div#expand{margin-left:auto;margin-right:auto;}