fenix-fox/chrome/hide_tabs_toolbar.css

/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/hide_tabs_toolbar.css made available under Mozilla Public License v. 2.0
See the above repository for updates as well as full license text. */

/* Hides tabs toolbar */
/* For OSX use hide_tabs_toolbar_osx.css instead */

/* Note, if you have either native titlebar or menubar enabled, then you don't really need this style.
 * In those cases you can just use: #TabsToolbar{ visibility: collapse !important }
 */

/* IMPORTANT */
/*
Get window_control_placeholder_support.css
Window controls will be all wrong without it
*/

:root[tabsintitlebar]{ --uc-toolbar-height: 40px; }
:root[tabsintitlebar][uidensity="compact"]{ --uc-toolbar-height: 32px }

#TabsToolbar{ visibility: collapse !important }

:root[sizemode="fullscreen"] #TabsToolbar > :is(#window-controls,.titlebar-buttonbox-container){
  visibility: visible !important;
  z-index: 2;
}

:root:not([inFullscreen]) #nav-bar{
  margin-top: calc(0px - var(--uc-toolbar-height,0px));
}

:root[tabsintitlebar] #toolbar-menubar[autohide="true"]{
  min-height: unset !important;
  height: var(--uc-toolbar-height,0px) !important;
  position: relative;
}

#toolbar-menubar[autohide="false"]{
  margin-bottom: var(--uc-toolbar-height,0px)
}

:root[tabsintitlebar] #toolbar-menubar[autohide="true"] #main-menubar{
  -moz-box-flex: 1;
  -moz-box-align: stretch;
  background-color: var(--toolbar-bgcolor,--toolbar-non-lwt-bgcolor);
  background-clip: padding-box;
  border-right: 30px solid transparent;
  border-image: linear-gradient(to left, transparent, var(--toolbar-bgcolor,--toolbar-non-lwt-bgcolor) 30px) 20 / 30px
}

#toolbar-menubar:not([inactive]){ z-index: 2 }
#toolbar-menubar[autohide="true"][inactive] > #menubar-items {
  opacity: 0;
  pointer-events: none;
  margin-left: var(--uc-window-drag-space-pre,0px)
}