userChrome.css

/* * Do not remove the @namespace line -- it's required for correct functioning
*/
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@namespace html url("http://www.w3.org/1999/xhtml");
@namespace svg url("http://www.w3.org/2000/svg");
/* set default namespace to XUL */

#TabsToolbar {
	border-width:1px !important;
	border-style: solid;
	border-color:transparent !important;
	margin-bottom:-4px !important;
	margin-top:1px !important;
	margin-left:40.00vw !important;
	}

#TabsToolbar .titlebar-placeholder[type="pre-tabs"] {
	display: none !important;
	}

#TabsToolbar, #tabbrowser-tabs, #nav-bar, #toolbar-menubar, #browser-panel {
	background-color:rgb(50, 50, 52) !important;
	}

#nav-bar {
	border-width:1px !important;
	border-style: solid;
	border-color:transparent !important;
	}
#nav-bar {
	margin-bottom:0px !important;
	margin-top:-29px !important;
	margin-right: 60vw !important;
	margin-left: -0.2vw!important;
	}

#urlbar-container {
	border:none !important;
	top:0px;
	padding-left: 0px !important;
	}

#nav-bar, #urlbar-container, #urlbar, #TabsToolbar, #tabbrowers-tabs {
	min-width: unset !important;
	width: unset !important;
	max-width: unset !important;
	}

#toolbar #urlbar-container {
	box-sizing:border-box!Important;
	background:none !important;
	z-index:1!important;
	}

#page-action-buttons {
  display: none !important;
	}

#context-sendpagetodevice, #context-sep-sendpagetodevice,
#context-sendlinktodevice, #context-sep-sendlinktodevice,
#context_sendTabToDevice, #context_sendTabToDevice_separator {
  display: none !important;
	}

.tabbrowser-tab {
  min-width: 1em !important;
  clip-width: 1em !important;
	}

.browserContainer>.browserStack>browser{
     overflow-y: scroll;
     overflow-x: hidden;
     margin-right: -17px;
     margin-bottom: -0px;
	}

.tab-close-button {
  opacity: 0;
}
.tab-content:hover .tab-close-button {
  opacity: 1;
  transition: opacity 200ms ease-in-out;
}

.urlbar-history-dropmarker {
  display: none !important;
	}

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
@-moz-document url("chrome://browser/content/browser.xul")
{
  #PanelUI-button, #customization-panel-container,
  #customization-panelWrapper .panel-arrow,
  #ctr_panelui-button,
  #wrapper-ctr_panelui-button {
    -moz-box-ordinal-group: 0
  }

  #PanelUI-button {
    background-position: 100% 0, calc(100% - 1px) 0, calc(100% - 2px) 0;
  }
}

.tabbrowser-tab::before, .tabbrowser-tab::after {
display: none!important;
}

   /*Darken panels to match theme*/
.panel-arrow { filter: invert(33%); }
.panel-subview-body,#appMenu-zoomReset-button {
  color: var(--lwt-text-color) !important;
  background: var(--url-and-searchbar-background-color) !important;}
.panel-subview-footer,[class^="PanelUI-"] {
  color: var(--lwt-text-color) !important;
  background: var(--toolbar-bgcolor) !important;}
#PopupAutoCompleteRichResult .ac-title-text{
  color: var(--lwt-text-color) !important;
  filter: opacity(.7);}
#PopupAutoCompleteRichResult .autocomplete-richlistbox {
  background: var(--url-and-searchbar-background-color) !important;}
/*stops possible clashes with extension popups*/
  .webextension-popup-browser {
  background: #fff;}

/*Dark context menu*/
menupopup, popup,
popup > menu > menupopup,
menupopup > menu > menupopup {
    -moz-appearance: none !important;
    background: #202020 !important;
    border: 1px solid #606060 !important;
    padding: 6px 0px 6px 0px  !important;}

menupopup menuseparator {
    -moz-appearance: none !important;
    background: #808080 !important;
    margin: 2px 6px 2px 6px !important;
    padding: 0 !important;
    border-top: none !important;
    border-color: transparent !important;}

menupopup menu, menuitem{
    /*-moz-appearance: none !important;*/
    /*font-size: 9pt !important;*/
    /*margin: 3px 0px 3px 0px !important;*/
    color: #E0E0E0!important;}

menupopup menu:hover, menuitem:hover {
    /*-moz-appearance: none !important;*/
    color:#E4E4E4 !important;
    /*font-size: 9pt !important;*/
    /*margin: 3px 0px 3px 0px !important;*/
    background-color:#101010 !important;}

.menu-right{
    filter: invert(95%)!important;
}

#context-stop image:hover,
#context-bookmarkpage image:hover,
#context-navigation,
#context-sep-navigation,
#context-back image:hover,
#context-forward image:hover,
#context-reload image:hover {
    color: #E0E0E0!important;
    background: #181818 !important;
}

#urlbar html|input.textbox-input::-moz-selection {
    background-color: green !important;
}

#urlbar[focused="true"] {
 border-color: green !important;
}

.tab-line[selected]{
    background-color: #f8f8f2 !important;
        height: 2px !important;

[class^="verified"] > #identity-icon { max-width: 0px !important; }