Hello!

In $DAYJOB, right now we are working on a larger redesign of our
customer facing web app.  As such I'm knee deep in css these days.  I've
noticed there are some holes in the completion keywords, and I'd like to
start addressing those.  Hence the first, simple starting-point patch.
Before I continue adding patches, I'd like some pointers as to how I
should structure them.  For example - lots of keywords are now shared
between grid and flex. An example is `align-content', which is now
under a section devoted to flex.  However, there are some newer,
grid-related completion keywords that are not in this section, nor
anywhere else.  See line 306 in css-mode.el. I guess the solution here
is to add `start' and `end' there, but I want to check first.

Should I add several, smaller patches, or one big correction of most of
the things I see at the moment?  

Best,
Theodor Thornhill