【media】
<!DOCTYPE html>
<html>
<head>
<style type='text/css'>
.left {
float: left;
}
.right {
clear: left;
float: left;
}
@media ( min-width : 500px) {
.right {
float: right;
clear: none;
}
}
</style>
</head>
<body>
<p>
<span class="left">Some text. </span>
<span class="right">Some occasionally-floated text.</span>
</p>
</body>
</html>
