Add support for the `/` and `,` separators

[M-J-Robbins]

Hi, love the site.

One thing I think that is missing the the / that comes up in some CSS functions such as border-radius: 50% / 2em or background:url(image.png) right top / 150px auto no-repeat

Also maybe the , that separates multiple backgrounds, box-shadows, etc. box-shadow:1px 1px red, -1px -1px blue;

Not too sure what they're technically called, I call them both separators but would be interested to know.

[sakamies]

Hmm right, didn't think of those cases. Thank you! I'll try to get these added this fall.