[css] css - position div to bottom of containing div

Add position: relative to .outside. (https://developer.mozilla.org/en-US/docs/CSS/position)

Elements that are positioned relatively are still considered to be in the normal flow of elements in the document. In contrast, an element that is positioned absolutely is taken out of the flow and thus takes up no space when placing other elements. The absolutely positioned element is positioned relative to nearest positioned ancestor. If a positioned ancestor doesn't exist, the initial container is used.

The "initial container" would be <body>, but adding the above makes .outside positioned.