Improve webview tab activation and styling

Ensure the webviews container is visible when converting a home tab to a webview, and activate the converted tab in the UI. Also, update webview CSS to set width and height to 100% for better layout consistency.

renderer/style.css

@@ -136,6 +136,8 @@ html, body {
 
 #webviews webview {
   flex: 1;
+  width: 100%;
+  height: 100%;
   border: none;
   display: none;
 }