/* Hide tabs unless cursor is on top of toolbar */
/* This does not support multi-row tabs */

:root:not([customizing]) #titlebar{
  margin-bottom: calc(0px - var(--tab-min-height));
  transition: margin-bottom 48ms ease-out;
}
#TabsToolbar:not([customizing]){ visibility: hidden; }
#navigator-toolbox:hover > #titlebar{ margin-bottom: 0; }
#navigator-toolbox:hover > #titlebar > #TabsToolbar{ visibility: visible; }