Drop shadow with different blur radii

This is faking a shadow as it would come from a point light placed above the bottom left corner of the box.

by Sebastian Zartner

HTML

<div></div>

CSS

div {
  margin: 40px;
  width: 400px;
  aspect-ratio: 1;
  box-shadow: 0 5px 5px -2.5px black, -5px 0 5px -2.5px black, 40px 0 40px 10px black, 0 -20px 20px 0 black;
}