<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
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<html lang="en">
<head>
<meta charset="UTF-8">
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<title>CodePen - contant page</title>
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<style>
section {
margin: 4em 0;
}
section:first-child {
margin-top: 0;
}
.cf-left-nav-bar h2 {
font-size: 16px;
text-transform: uppercase;
}
.cf-left-nav-bar ul {
list-style: none;
