Multiple box-shadows can be applied to the same DOM element. The box-shadow
property accepts a comma-separated list of box-shadow
directives.
Here is a pretty nasty looking example from the MDN docs:
/* Any number of shadows, separated by commas */
box-shadow: 3px 3px red, -1em 0 0.4em olive;
Here is a more practical example:
box-shadow: 0 0 0 2px #4caf50,
0 3px 5px 0 rgba(0,0,0,0.5);
This gives the effect of a solid border with some shadow for depth.
Multiple shadows has pretty robust browser support.