I am not sure if this change is now but it struck me just now.
The Google navigation bar at the top in Gmail is no longer black in color. It shows a color based on the theme you have selected and the end result looks much better.
On most other Google services though, it continues to use the black color.
Google has been experimenting with some changes that might soon enable them to get rid of this navigation bar completely.
For now, you would have to live with it. At least it does not look that bad anymore in Gmail!