<!DOCTYPE HTML>
<html>
<body style="overflow:hidden; height:3000px;
             background-image:url(repeatable-diagonal-gradient.png);
             background-repeat:no-repeat;
             background-position:0 300px;">
  <div style="position:absolute; background:black; top:0; left:0; width:500px; height:400px;"></div>
</body>
</html>