HTML: 404 page

<html>
<head>
<!-- codepen: https://codepen.io/ThatGuySam/pen/CytDA by ThatGuySam -->
<style>
.hit-the-floor {
  color: #fff;
  font-size: 12em;
  font-weight: bold;
  font-family: Helvetica;
  text-shadow:
    0 1px 0 #ccc,
    0 2px 0 #c9c9c9,
    0 3px 0 #bbb,
    0 4px 0 #b9b9b9,
    0 5px 0 #aaa,
    0 6px 1px rgba(0,0,0,.1),
    0 0 5px rgba(0,0,0,.1),
    0 1px 3px rgba(0,0,0,.3),
    0 3px 5px rgba(0,0,0,.2),
    0 5px 10px rgba(0,0,0,.25),
    0 10px 10px rgba(0,0,0,.2),
    0 20px 20px rgba(0,0,0,.15);
}

.hit-the-floor {
  text-align: center;
}

body {
  background-color: #f1f1f1;
}
</style>
</head>
<body>
<div class="hit-the-floor">404</div>
</body>