vertical_tabs: Remove opacity changes from titlebar

This makes window controls show up on Linux and fixes them disappearing
from non-focused window on Windows

chrome/vertical_tabs.css

@@ -104,4 +104,9 @@ scrollbox[orient="horizontal"]{
 #scrollbutton-up,
 #scrollbutton-down{
   display: var(--uc-scrollbutton-display,initial);
-}
+}
+#titlebar{
+  will-change: none !important;
+  transition: none !important;
+  opacity: 1 !important;
+}