Rated 5 out of 5 stars

Great! but....
1. Do you now why this style doesn´t works ell with USM?
#main-window[tabsontop="true"][sizemode="normal"] #TabsToolbar {
padding-left: 2px !important;
I try the same code in Stylish and it works fine. I also tru to use the "margin-left" property and it works well with USM and Stylsih, but at Firefox start, sometimes you have to wait a bit because USM takes some time on load. With "padding-left" in Stylish it doesn't happen.
2. Here is the complete code: http://tinypaste.com/725778d0.
If you can fix it,it would be appreciated.

This review is for a previous version of the add-on (0.9.1-signed). 

Hi, the code that you pasted here and also on the tinypaste, both work in both USM and Stylish, but there is something wrong with your styles, they are making the appmenu disappear. I don't exactly understand what you want to do with the styles.