userChrome.css

#toolbar-menubar[inactive] + #TabsToolbar {
  //visibility: collapse;
}

#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
  display: none;
}

splitter {
  padding: 5px;
  opacity: 0;
  margin: -6px;
}

#back-button[disabled], #forward-button[disabled] {
  visibility: hidden;
}
.scrollbutton-up, .scrollbutton-down, #new-tab-button, #alltabs-button {
  visibility: collapse;
}

.tabbrowser-tab[pinned][first-visible-tab]{
  padding-left: 34px !important;
}

/* Minimalist Theme */

#back-button, #forward-button { opacity: 0.2; }

tab[pinned] {
  opacity: 0.4;
}
tab[pinned]:hover {
  opacity: 1;
}

#titlebar-buttonbox,
#TabsToolbar,
#PersonalToolbar,
#urlbar,
#nav-bar {
  background: #31363b !important;
}

#urlbar {
  border: none !important;
  box-shadow: none !important;
}

.tab-close-button.tab-close-button {
  visibility: collapse !important;
}

#identity-box, #page-action-buttons, #nav-bar toolbarbutton { opacity: 0.2; }

#page-action-buttons:hover,
#identity-box:hover,
#nav-bar toolbarbutton:hover{
  opacity: 1;
}
#nav-bar toolbaritem {
  border: none !important;
}
#nav-bar #PanelUI-button {
  padding-left: 15px;
}

#urlbar .urlbar-input-box {
    text-align: center;
}

/* Autohide Tabs */
#TabsToolbar {
  min-height: 40px !important;
  margin-top: -40px !important;
  transition: all 0.3s ease 0s !important;
  -moz-box-ordinal-group: 2 !important;
  opacity: 0.6;
}
#nav-bar {
  z-index: 3;
}
#navigator-toolbox {
  transition: all 0.3s ease 0s !important;

}
#navigator-toolbox:hover {
  margin-bottom: -39px !important;
  transition: all 0.3s ease 0s !important;
}
#navigator-toolbox:hover > #TabsToolbar {
  margin-top: -1px !important;
  transition: all 0.3s ease 0s !important;
  opacity: 1;
}

 
/* Tabs don't move when dragging. */
#TabsToolbar[movingtab] {
  padding-bottom: -0px !important;
}
#TabsToolbar[movingtab] > .tabbrowser-tabs {
  padding-bottom: -0px !important;
  margin-bottom: -0px !important;
}
#TabsToolbar[movingtab] + #nav-bar {
  margin-top: -0px !important;
  pointer-events: none;
}



/* Tab Line At Bottom */
.tab-line {
  -moz-box-ordinal-group: 2;
  min-height: 3px;
}