Bootstrap Nested Columns

The nested columns are shown, where two columns of col-md-6 are inserted into single col-md-6.

<!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 class="container-fluid">
        <div class="row">
            <div class="col-sm-6" style="background-color:yellowgreen;">
                .col-sm-6
                <div class="row">
                    <div class="col-sm-6" style="background-color:aquamarine;">.col-sm-6</div>
                    <div class="col-sm-6" style="background-color:slategrey;">.col-sm-6</div>
                </div>
            </div>
            <div class="col-sm-6" style="background-color:lavender;">.col-sm-6</div>
        </div>
    </div>
</body>
</html>

Output