mdo/wtf-html-css — pull request #44 by benbrowning (2014-04-11 12:23:06+00:00)
Title: Adding overview of z-index, and the aspects of it that can catch you out...

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When I saw your page, I thought it might benefit an entry on z-index, as that is definitely an area that can cause a lot of head-scratching. Here's my attempt at that.