#TabsToolbar .tabbrowser-arrowscrollbox,
#TabsToolbar .arrowscrollbox-scrollbox,
#TabsToolbar .scrollbox-innerbox {
  display: block !important;
}
.scrollbutton-up,
.arrowscrollbox-overflow-start-indicator,
.scrollbutton-down,
.arrowscrollbox-overflow-end-indicator {
  display: none !important;
}
.tabbrowser-tab {
  min-height: var(--tab-min-height) !important;
  vertical-align: bottom !important;
}
.tabbrowser-tab {
    min-width: 100px !important;
}   
@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
  
.tabbrowser-tab:not([pinned]):not(:hover) .tab-close-button {
  visibility: collapse !important;
}
.tabbrowser-tab:not([pinned]):hover .tab-close-button {
  visibility: visible !important;
  display: block !important;
}