Super Rated 5 out of 5 stars
A really lovely theme, my favorite for Firefox and Thunderbird.
With Thunderbird, I had to 1) use "big" symbols in the button pane and 2) move each button out of the pane and re-insert it aftwerwards, otherwise all labels appeared next to the symbols instead of under them - which fills the button pane too fast.
Support for Lightning is only up to v0.8 - I'm still waiting for 0.9 to be supported (0.9 looks little bit strange with Walnut theme, and not all features work).
Anyway, a really good theme which is worth 5 stars.