My custom userChrome.css (intended to be used with Tree Style Tab) (barely works and is very buggy)

userChrome.css

#TabsToolbar {
  display: none;
}

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

#nav-bar {
	position: absolute !important;
  padding-top: 22px !important;
  -moz-window-dragging: drag;
  background-color: var(--lwt-accent-color) !important;;
}

#nav-bar {
  toolbarbutton:not(#unified-extensions-button):not(#downloads-button),
  urlbar-go-button,
  .urlbar-page-action {
    display: none !important;
  }
}

#urlbar-container {
  margin-inline: 0px !important;
  margin-inline-start: 2px !important;
}

#sidebar-box {
  margin-top: 60px;
}

#nav-bar[urlbar-exceeds-toolbar-bounds="true"] {
  width: 100% !important;
}

#nav-bar-customization-target {
  background-color: var(--toolbar-bgcolor);
}

#tracking-protection-icon-container,
#identity-box {
  display: none;
}

#urlbar[open] {
  #tracking-protection-icon-container,
  #identity-box {
    display: inherit;
  }
}

#toolbar-menubar {
  flex-direction: row-reverse;
}

.toolbarbutton-icon {
  width: 28px !important;
  height: 28px !important;
  padding: 6px !important;
}