<!DOCTYPE HTML> <html> <head> <meta charset="utf-8"> <title>Correctly masked page</title> <style> .box { position: relative; width: 420px; height: 420px; } </style> </head> <body> <div class="box" style="background-color: black;"> </div> <div class="box" style="background-color: white;"> </div> </body> </html>
