minor: reconsider background color for normal operations/messages

[vvuk]

Hello! ungit is great, and I'm deploying it in some docker dev containers to make it easy for users to do some quick git ops without having to ssh in.

One question I've gotten a few times though -- the "light red" background on some things made a few users think that there was an error, when it's actually just a normal message; this seems to be on the staging CSS class, e.g.:

I totally realize that this is a large part how one interprets that color/personal preference/etc., but perhaps something less-red that still stands out, e.g. darkslateblue:

Totally minor though!