Firefox Quantum Dark Theme Fixes

userChrome.css

:root {
	--browser-background: #38383d;
}

/* Prevents New Tab White Flash */
tabbrowser tabpanels {
	background-color: var(--browser-background) !important;
}

/* Dark Theme for Context Menu Top Row */
#context-navigation {
	background-color: var(--uc-dark-bkgnd-color) !important;
}

/* Dark Theme for Sidebar */
#sidebar-box {
	background-color: hsl(240, 7%, 5%) !important;
}

toolbarbutton[checked="true"]:not([disabled="true"]) {
	color: inherit !important;
}

#sidebar-header, .sidebar-splitter {
	border-color: hsl(240, 3%, 20%) !important;
}

.sidebar-placesTree {
	color: #aaa !important;
}

/* Dark Theme for Menus */
:root {
	--uc-dark-bkgnd-color: #2b2b2b;
	--uc-light-bkgnd-color: #363636;
	--uc-active-color: #404040;
	--uc-text-color: rgb(195, 198, 201);
	--uc-border-color: #767676;
}

#mainPopupSet menupopup menuitem,#mainPopupSet menupopup menu {
	min-height: 24px !important;
}

.panel-arrowcontent,
#placesContext,
#alltabs-popup .arrowscrollbox-scrollbox,
#contentAreaContextMenu,
.textbox-contextmenu,
#mainPopupSet menupopup,
#bookmarks-menu-button menu menupopup {
	border: 1px solid var(--uc-border-color) !important;
	background: var(--uc-dark-bkgnd-color) !important;
	color: var(--uc-text-color) !important;
}

#alltabs-popup menuitem,
#bookmarks-menu-button menu menupopup .subviewbutton {
	color: var(--uc-text-color) !important;
}
#mainPopupSet menupopup,
#mainPopupSet menupopup menuitem,
#mainPopupSet menupopup menu,
#alltabs-popup,
#bookmarks-menu-button menu menupopup {
	-moz-appearance: none !important;
	border: none;
}

.panel-subviews,
#mainPopupSet menupopup,
#bookmarks-menu-button menu menupopup > hbox,
.search-panel-header.search-panel-current-engine,
.search-panel-current-input, panelview,
.PanelUI-subView {
	background-color: var(--uc-dark-bkgnd-color) !important;
}

#BMB_bookmarksPopup {
	background-color: unset !important;
}

.subviewbutton:hover,
#PanelUI-contents toolbarbutton:hover,
#mainPopupSet menupopup menuitem:hover,
#mainPopupSet menupopup menu:hover,
#PanelUI-footer toolbarbutton:not(#PanelUI-quit):hover {
	background-color: var(--uc-active-color) !important;
}

#PanelUI-footer *,
panelview toolbarbutton.subviewbutton .toolbarbutton-text,
#downloadsFooter,#customizationui-widget-panel label,
.autocomplete-richlistitem .ac-title,
#widget-overflow-list toolbarbutton,
#mainPopupSet menupopup menuitem,
#mainPopupSet menupopup menu,
#bookmarks-menu-button menu menupopup,
#PopupSearchAutoComplete .autocomplete-tree.plain.search-panel-tree,
#PanelUI-contents toolbarbutton,
#sidebar-switcher-target,
#alltabs_containersTab {
	color: var(--uc-text-color)!important;
}
#alltabs-popup,
#alltabs_containersMenuTab {
	border: none !important;
}
#alltabs_containersMenuTab {
	-moz-appearance: none !important;
	background-color: transparent !important;
}

#placesContext,
#contentAreaContextMenu,
#contentAreaContextMenu menupopup,
#page-action-mainView,
.textbox-contextmenu {
	-moz-appearance: none !important;
	background-color: var(--uc-dark-bkgnd-color) !important;
	border: none;
}

#placesContext menuitem,
#contentAreaContextMenu menuitem,
#contentAreaContextMenu menu,
.textbox-contextmenu menuitem {
	color: var(--uc-text-color) !important;
	-moz-appearance: none;
}

#placesContext menuitem,
#contentAreaContextMenu #context-navigation:not([hidden])~menu,
#contentAreaContextMenu #context-navigation:not([hidden])~menuitem {
	min-height: 24px !important;
	height: 24px;
}

#placesContext menuitem[disabled="true"],
#contentAreaContextMenu menuitem[disabled="true"],
#mainPopupSet menupopup menuitem[disabled="true"],
#BMB_bookmarksPopup menuitem[disabled],
.textbox-contextmenu menuitem[disabled] {
	color: #888 !important;
}

#placesContext menuitem:hover,
#contentAreaContextMenu menuitem:hover,
#contentAreaContextMenu menu:hover,
#contentAreaContextMenu menu[open],
.textbox-contextmenu menuitem:hover {
	background-color: var(--uc-active-color);
	border: none;
}

.autocomplete-richlistbox {
	background-color: var(--uc-dark-bkgnd-color) !important;
}
#PopupAutoCompleteRichResult .ac-title,
#PopupAutoCompleteRichResult .search-one-offs,
.search-panel-input-value {
	color: var(--uc-text-color) !important;
}

#PopupSearchAutoComplete {
	background-color: var(--uc-light-bkgnd-color) !important;
	color: var(--uc-text-color) !important;
}

.search-panel-one-offs,
.downloadsPanelFooterButton:not(:hover),
#overflowMenu-customize-button:not(:hover) {
	background-color: var(--uc-light-bkgnd-color) !important;
}