俺もこの前別のスレで教えてもらったブックマークツールバーがにょきにょき隠れるやつ
/*Auto Hide book mark bar*/

treechildren::-moz-tree-twisty {
-moz-appearance: none !important;
padding-right: 0px !important;
padding-top: 0px !important;
width: 0px !important;
list-style-image: none !important; }
#navigator-toolbox
{
position: relative;
transition: all 0.3s ease 0s !important;
}
#PersonalToolbar
{
/*overflow: hidden;*/
margin-top: -20px !important;
transition: all 0.3s ease 0s !important;
}
#navigator-toolbox:hover
{
margin-bottom: -20px !important;
transition-delay: 0s !important;
}
#navigator-toolbox:hover > #PersonalToolbar
{
margin-top: 0 !important;
transition-delay: 0s !important;
}