Overlap two centered elements using CSS flexbox

Question

I\'m trying to absolutely center two elements in the middle of the page, with one behind the other. The intent is to have a page that is fully responsive with a circle in the mi

Answer 1

Not sure if that'll do it, but you could simply add to your :after

position: absolute;
top   : 0;
left  : 0;
bottom: 0;
right : 0;

fiddle: http://jsfiddle.net/ccyd6xh1/

Update that was a quick draft, and was not absolutely responsive. If you want the effect the really follow your sphere and its size, you should add the :after on the sphere element and not its container, and use % width and height (here the glow grows to 130% of the sphere size):

http://jsfiddle.net/tjoo739y/