<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>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<link rel="shortcut icon" type="image/x-icon" href="https://static.codepen.io/assets/favicon/favicon-aec34940fbc1a6e787974dcd360f2c6b63348d4b1f4e06c77743096d55480f33.ico" />
<link rel="mask-icon" type="" href="https://static.codepen.io/assets/favicon/logo-pin-8f3771b1072e3c38bd662872f6b673a722f4b3ca2421637d5596661b4e2132cc.svg" color="#111" />
<title>CodePen - Pure CSS Rotating Spiral Image Gallery</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/modernizr/2.8.3/modernizr.min.js" type="text/javascript"></script>
<style>
html {
height: 100%;
perspective: 40em;
background: dimgrey;
}
.strip {
position: relative;
padding: 0;
margin: 6em 0 0;
list-style: none;
transform-style: preserve-3d;
}
.tile {
position: absolute;
top: 50%;
left: 50%;
margin: -1.5em;
width: 3em;
height: 3em;
