Custom userChrome.css for firefox 57 for auto-hiding the navigation bar and bookmark bar

userChrome.css

/* Auto-hide toolbar */
:root[uidensity=compact] #navigator-toolbox {
  --nav-bar-height: 33px;
}

:root:not([uidensity]) #navigator-toolbox {
  --nav-bar-height: 39px;
}

:root[uidensity=touch] #navigator-toolbox {
  --nav-bar-height: 41px;
}

#navigator-toolbox {
  --tabbar-height: calc(var(--tab-min-height) + var(--space-above-tabbar));
  --trigger-area-height: 5px;
}

:root[chromehidden~="toolbar"] #navigator-toolbox {
  --tabbar-height: 0.1px;
}

#toolbar-menubar {
  margin-top: 0px !important;
}

:root[sizemode="normal"][chromehidden~="menubar"] #TabsToolbar,
:root[sizemode="normal"] #toolbar-menubar[autohide="true"][inactive] + #TabsToolbar {
  padding-top: var(--space-above-tabbar) !important;
}

#nav-bar, #PersonalToolbar {
    -moz-window-dragging: default;
}

:root:not([customizing]) #nav-bar
{
  overflow-y: hidden;
 	 max-height:0;
  min-height:0 !important;
  padding-top:0 !important;
  padding-bottom:0 !important;
  opacity: 0;
}

:root:not([customizing]) :hover > #nav-bar,
:root:not([customizing]) #nav-bar:focus-within {
  max-height: var(--nav-bar-height);
  opacity: 1;
  transition: opacity 0.15s ease-in, max-height 0.15s linear;
}

:root:not([customizing]) #navigator-toolbox {
  max-height: calc(var(--tabbar-height) + var(--trigger-area-height));
  min-height: var(--tabbar-height);
  margin-bottom: calc(-1 * var(--trigger-area-height));
}

:root:not([customizing]) #navigator-toolbox:hover,
:root:not([customizing]) #navigator-toolbox:focus-within {
  max-height: calc(var(--tabbar-height) + var(--nav-bar-height));
  margin-bottom: calc(0px - var(--nav-bar-height));
}

:root:not([customizing]) #PersonalToolbar {
  max-height: 0 !important;
  min-height: 0.1px !important;
  opacity: 0;
  transition: opacity 0.15s ease-in !important;
}

:root:not([customizing]) :hover > #PersonalToolbar,
:root:not([customizing]) #navigator-toolbox:focus-within #PersonalToolbar {
  max-height: 4em !important;
  opacity: 1;
}
/* End of Auto-hide toolbar */

looks cool, thanks a lot 💃

just to let you know, this is no longer working.