Editor: fix iframe stacking with absolute positioning

Author: pepc84

editor/index.html

@@ -67,13 +67,11 @@
     #preview-area {
       flex: 1;
       background: #111;
-      display: flex;
-      align-items: center;
-      justify-content: center;
       overflow: hidden;
+      position: relative;
     }
     #preview-area canvas { display: block !important; }
-    #preview-area iframe { width: 100%; height: 100%; border: none; display: block; }
+    #preview-area iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; border: none; display: block; }
 
     #preview-placeholder { color: #555; font-size: 13px; text-align: center; line-height: 2.2; }
     #preview-placeholder kbd {