Bug 1506341 - Let the autohiding menu bar match the tab bar's height. r=stransky

Differential Revision: https://phabricator.services.mozilla.com/D11550

--HG--
extra : moz-landing-system : lando

browser/themes/linux/browser.css

@@ -646,6 +646,15 @@ notification[value="translation"] menulist > .menulist-dropmarker {
     visibility: visible;
   }
 
+  /* When temporarily showing the menu bar, make it at least as tall as the tab
+   * bar such that the window controls don't appear to move up. */
+  :root[tabsintitlebar] #toolbar-menubar[autohide="true"] {
+    height: var(--tab-min-height);
+  }
+  :root[tabsintitlebar][sizemode="normal"] #toolbar-menubar[autohide="true"] {
+    height: calc(var(--tab-min-height) + var(--space-above-tabbar));
+  }
+
   /* Add extra space to titlebar for dragging */
   :root[sizemode="normal"][chromehidden~="menubar"] #TabsToolbar,
   :root[sizemode="normal"] #toolbar-menubar[autohide="true"][inactive] + #TabsToolbar {

browser/themes/shared/tabs.inc.css

@@ -6,18 +6,15 @@
 %filter substitution
 %define horizontalTabPadding 9px
 
-#titlebar,
-#tabbrowser-tabs {
+:root {
   --tab-min-height: 33px;
 }
 
-:root[uidensity=compact] #titlebar,
-:root[uidensity=compact] #tabbrowser-tabs {
+:root[uidensity=compact] {
   --tab-min-height: 29px;
 }
 
-:root[uidensity=touch] #titlebar,
-:root[uidensity=touch] #tabbrowser-tabs {
+:root[uidensity=touch] {
   --tab-min-height: 41px;
 }