renamed userChrome.css

.config/mozilla/firefox/chrome/hiddenUserChrome.css

@@ -0,0 +1,25 @@
+#tabbrowser-tabs, #tabbrowser-tabs > .tabbrowser-arrowscrollbox {
+	min-height: 0 !important;
+}
+
+/* Thanks to @Speravir for making it work again in the latest versions. */
+/*
+#tabbrowser-tabs tab[first-visible-tab="true"][last-visible-tab="true"] {
+	visibility: collapse;
+}*/
+
+
+#navigator-toolbox{
+	visibility: collapse !important; }
+
+/* I don't use tabs so I just hide the new tab button. You should be able to use a similar trick as the rule above with
+css siblings selectors if you want to keep it when the tab bar is visible. */
+/*
+#tabbrowser-tabs .tabs-newtab-button { 
+	visibility: collapse !important;
+}
+*/
+
+#tabbrowser-tabs tab {
+	min-height: var(--tab-min-height)
+}