<!DOCTYPE html>
<html>
<head>
<title></title>
<style type="text/css">
div.clazz {
height: 100px;
width: 100px;
background-color: gray;
}
div#clazz {
height: 100px;
width: 100px;
background-color: blue;
}
div[test] {
height: 100px;
width: 100px;
background-color: red;
}
</style>
</head>
<body>
<div class="clazz"></div>
<div id="clazz"></div>
<div test="test1"></div>
</body>
</html>