Today we’re going to take a quick look at a few special CSS keywords you can use on any CSS property:
unset. Also, we will ask where and when to use them to the greatest effect, and if we need more of those keywords.
The first three were defined in the Cascading Level 3 spec, while
revert was added in Cascading Level 4. Despite 4 still being in draft
revert is already supported.
the MDN revert page,
Chris Coyier’s page,
and my test page