[mirotalksfu] - extend whiteboard functions

public/css/Room.css

@@ -52,11 +52,11 @@
     font-family: 'Comfortaa';
 }
 
-html {
-    height: 100%;
-}
-
+html,
 body {
+    width: 100%;
+    height: 100%;
+    overflow: hidden;
     background: var(--body-bg);
 }