<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>CSS Frameworks | Responsive</title>
    <meta content="width=device-width, initial-scale=1" name="viewport">
    <!--link Bootstrap Framework-->
    <link href="assests/css/bootstrap.min.css" rel="stylesheet">
    <style>
        section {
            height: 400px;
            border: 1px solid red;
        }

        section > div {
            border: 1px solid blue;
        }
    </style>
</head>
<body>

<!--container (keep sp