Update dark theme color to match mock

Mock: https://docs.google.com/presentation/d/15JadcGi5k1_0znUN_XdFpU7UxeXwxjK3Y7LxvhW5ETM/edit?ts=5e1cc430#slide=id.g85fff7c452_76_21
Screenshot:
https://screenshot.googleplex.com/ytBaVdCCto0.png
https://screenshot.googleplex.com/TppopvRTG2t.png
https://screenshot.googleplex.com/cndtG9eKopv.png
https://screenshot.googleplex.com/0zPK9qaTqrY.png
https://screenshot.googleplex.com/mMRCbvq8AYT.png

Test: Manually
Fixes: 158587080
Change-Id: I48a20b13e133467d6e30c9c94ae0594df48cd019