fenix-fox/chrome/dark_context_menus.css

/* Makes context menus dark */
/* Uses dark theme colors but does not respect dark theme variables (they wouldn't work on sidebar context menu) */

:root{
  --uc-menu-bkgnd: rgb(74,74,79);
  --uc-menu-color: rgb(230,230,230);
  --uc-menu-dimmed: rgba(255,255,255,0.1);
  --uc-menu-disabled: rgb(50,50,50);
}

panel richlistbox,
panel tree,
panel button,
panel menulist,
panel textbox,
menupopup,
menu,
menuitem{ -moz-appearance: none !important; }

menulist,
menuitem,
menu{ min-height: 1.8em }

panel menulist{ border: 1px solid transparent }

panel richlistbox,
panel tree,
panel button,
panel menulist,
panel textbox,
menupopup:not(#BMB_bookmarksPopup),
#main-menubar > menu > menupopup,
#context-navigation{
  color: var(--uc-menu-color) !important;
  padding: 2px;
  background-color: var(--uc-menu-bkgnd) !important;
  border-color: var(--uc-menu-disabled) !important;
}

panel menulist:hover, panel menulist[open]{ border-color: Highlight !important; }

#editBMPanel_folderMenuList > menupopup > menuitem{ color: var(--uc-menu-color) !important; }

panel treechildren::-moz-tree-row(selected),
panel button:hover,
menu:hover,
menu[_moz-menuactive],
menu[open],
menuitem:hover,
menuitem[_moz-menuactive]{
  background-color: var(--uc-menu-dimmed) !important;
  color: inherit !important;
}

menu[disabled="true"],
menuitem[disabled="true"]{ color: var(--uc-menu-disabled) !important; }

menu:not(.subviewbutton) > .menu-right{ filter: invert(1) }