<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8>
<title>valid width and height</title>
</head>
<body>
<img src="url" width="0" height="0" alt="bar"><!-- img with 0 value for width and height -->
<img src="url" width="10" height="10" alt="bar"><!-- img with positive values for width and height -->
</body>
</html>