fix: shell ui layout when WCO is not enabled

Author: samuelmaddock

packages/shell/browser/ui/webui.html

@@ -49,15 +49,15 @@
 
       #tabstrip {
         width: 100%;
-        height: calc(env(titlebar-area-height) + 1px);
+        height: calc(env(titlebar-area-height, 31px) + 1px);
       }
 
       .tab-container {
         position: fixed;
         left: env(titlebar-area-x);
         top: env(titlebar-area-y);
         width: env(titlebar-area-width);
-        height: calc(env(titlebar-area-height) + 1px);
+        height: calc(env(titlebar-area-height, 31px) + 1px);
         display: flex;
         flex-direction: row;
       }