<!DOCTYPE html>
<html>
<head>
<style>
div {
  float: left;
  width: 300px;
  height: 200px;
  background: url(repeatable-diagonal-gradient.png);
}
</style>
</head>
<body>
  <div id="a" style="width:0"></div>
  <div id="b" style="opacity:0.999"></div>
</body>
</html>