Gibber-gabber
CSS relative absolute positioning
Jason Scragz over 3 years ago

A couple weeks ago, while doing some unrelated research, I came across a technique that I had somehow never heard of for absolute positioning in CSS. I want to post it here in case anyone else has missed out on this one.

There have been quite a few times where I wanted a div to be positioned absolutely and to have it’s top/left/etc. to be specified from its staticly-positioned parent, and not from the viewport. It turns out that all you need to do is give the parent position: relative and you can do exactly that.

Here’s the original article I read that goes in way more depth.