New file

chrome/navbar_tabs_responsive_oneliner.css

@@ -0,0 +1,47 @@
+/*Make tabs and navbar appear side-by-side tabs on right */
+
+/* IMPORTANT */
+/*
+Get window_control_placeholder_support.css
+Window controls will be all wrong without it
+*/
+
+/* Toolbars will be shown normally if window width goes below the value below */
+/* Modify it to suit your needs */
+
+@media screen and (min-width: 1200px){
+  /* Modify these to change relative widths or default height */
+  #navigator-toolbox{
+    --uc-navigationbar-width: 40vw;
+    --uc-toolbar-height: 40px;
+  }
+  /* Override for other densities */
+  :root[uidensity="compact"] > #navigator-toolbox{ --uc-toolbar-height: 32px; }
+  :root[uidensity="touch"] > #navigator-toolbox{ --uc-toolbar-height: 40px; }
+
+  #TabsToolbar{ margin-left: var(--uc-navigationbar-width); }
+  #tabbrowser-tabs{ --tab-min-height: var(--uc-toolbar-height) !important; }
+  
+  /* This isn't useful when tabs start in the middle of the window */
+  .titlebar-placeholder[type="pre-tabs"],
+  .titlebar-spacer[type="pre-tabs"]{ display: none }
+  
+  #navigator-toolbox > #nav-bar{
+    margin-right:calc(100vw - var(--uc-navigationbar-width));
+    margin-top: calc(0px - var(--uc-toolbar-height));
+  }
+
+  /* Override style set in window_control_placeholder_support.css  */
+  #nav-bar::after{ display:none !important }
+
+  /* Rules specific to window controls on right layout */
+  @supports -moz-bool-pref("layout.css.osx-font-smoothing.enabled"){
+    .titlebar-buttonbox-container{ position: fixed; left: 0px; z-index: 3; }
+  }
+
+  /* 1px margin on touch density causes tabs to be too high */
+  .tab-close-button{ margin-top: 0 !important }
+
+  /* Hide dropdown placeholder */
+  #urlbar-container:not(:hover) .urlbar-history-dropmarker{ margin-inline-start: -28px; }
+}