<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>System Colors work for Canvas Drop-Shadow Filters</title>
</head>
<body>
<div style="width: 100px; height: 100px; background-color: black"></div>
<div style="width: 100px; height: 100px; background-color: GrayText"></div>
</body>
</html>