<html>
<head>
<style>
#container {
width: 300px;
}
#left {
float: left;
width: 100px;
height: 100px;
background: red;
}
#right {
float: right;
width: 100px;
height: 200px;
background: blue;
}
#clear1 {
clear: none;
width: 200px;
height: 50px;
background: green;
}
#clear2 {
clear: left;
width: 200px;
height: 50px;
background: green;
}
#clear3 {
clear: right;
width: 200px;
height: 50px;
background: green;
}
</style>
</head>
<body>
<div id="container">
<div id="left"></div>
<div id="right"></div>
<div id="clear1"></div>
<div id="clear2"></div>
<div id="clear3"></div>
</div>
</body>
</html>