💄 Add Firefox userChrome

os/firefox/userChrome.css

@@ -0,0 +1,47 @@
+#tabbrowser-tabs {
+  visibility: collapse;
+}
+#navigator-toolbox {
+  display: flex;
+  flex-flow: row wrap;
+}
+#titlebar {
+  order: 1;
+  max-width: 146px;
+}
+#titlebar #TabsToolbar {
+  background-color: var(--toolbar-bgcolor);
+  background-image: var(--toolbar-bgimage);
+}
+#titlebar #TabsToolbar .titlebar-spacer {
+  background-color: rgba(0, 0, 0, 0.05);
+  margin: 3px;
+  border-radius: 25%;
+  cursor: grab;
+}
+#titlebar #TabsToolbar .titlebar-spacer[type="pre-tabs"] {
+  display: none;
+}
+#nav-bar {
+  order: 0;
+  width: calc(100% - 146px);
+}
+#PersonalToolbar {
+  order: 2;
+}
+
+/* Update - Hides the new Firefox home + tab dropdown. If you want to 
+* keep/customize those buttons. remove the CSS below and adjust the widths above 
+* to get everything fitting in one line */
+#TabsToolbar .toolbar-items {
+  display: none;
+}
+
+#nav-bar {
+  order: 0;
+  width: 100%;
+}
+
+#sidebar-header {
+  visibility: collapse !important;
+}