Bootstrap Unequal Columns

Two different classes .col-md-3 and .col-md-9 are used to divide the row in ratio of 3:9

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Bootstrap Grid Example</title>
    <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
    <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"> </script>
</head>
<body>
    <div>
        <div class="row">
            <div class="col-md-3" style="background-color:yellow;">col-md-3</div>
            <div class="col-md-9" style="background-color:pink;">col-md-9</div>
        </div>
    </div>
</body>
</html>

Output