Here is a quick suggestion. These should be more neutral and easy on the eyes if you keep seeing a lot of gerrit. I wish there was a simple way to change the values in the css and upload a preview, but i did a view source on gerrit and I received quite a fright.
Leaving it to someone else to show us how this scheme looks:
1) backgroundColor -- no change 2) topMenuColor -- #DBDCFF 3) textColor -- no change (unless its possible to have different classes for different texts) 4) trimColor -- optional #A4A5BF 5) selectionColor -- #FFE4CE, alternate #F1F1FF