Great Addon! HOWTO: Dark Style Rated 5 out of 5 stars
This plugin is great and essential for productivity! I love it!
I found the default color scheme rather hard to distinguish between active/inactive pages. To change the tree tabs into a darker style, navigate to "about:config" and change the following value:
"extensions.treestyletab.tabbar.style" to "metal"
and you will get a nice dark metallic style! :)