Hi, I almost didn't see this! Thanks for working on this. (Click on each thumbnail below to enlarge.)
Here is what it looks like in PM 27.8.0a1 x86_64 (2018-01-31) on Ubuntu 14.04:
The Location and Search bars went really dark on this theme. Now, that may be a feature and not a bug?
(Edit: Actually, I rather like this, but I wish it were a little more translucent so I could see persona better. It looks as though Material Moon has intentionally completely opaque bars).
Nevertheless, the menu bar isn't grey any more, but the menu bar and the rest of the toolbars don't quite match.
Here's a screenshot without the Navigation toolbar:
There is some discoloration stretching horizontally across, and it doesn't blend together.
And here are screenshots of other popular personas to further illustrate this issue:
Two Little Birds
Three Wolf Moon Shirt
The last one also has the dark URL & Search bars:
For comparison, here are what a couple of these look like with the Default theme:
The menu and the rest of the toolbars blend together seamlessly.
I hope this is something that is fixable! Thanks for all the work you've done so far!