Fix sub-level twistees' margin bug Rated 5 out of 5 stars

edit the part in the twisty.css:
.tabbrowser-tabs[treestyletab-twisty-style="retro"][treestyletab-mode="horizontal"][treestyletab-allow-subtree-collapse="true"][treestyletab-tabs-indented="true"] .tabbrowser-tab[treestyletab-children]:not([pinned="true"]) .tab-icon , .tabbrowser-tabs[treestyletab-twisty-style="retro"][treestyletab-mode="horizontal"]:not([treestyletab-tabs-indented="true"]) .tabbrowser-tab[treestyletab-children][treestyletab-nest="0"]:not([pinned="true"]) .tab-icon { margin-left: 16px;}

This review is for a previous version of the add-on (0.11.2011020402).  This user has other reviews of this add-on.