<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div class="cover">
    <div class="cover-inner">
      <div class="box">WOW</div>
    </div>
  </div>
</body>
</html>
body {
  margin: 0;
}

.cover {
    background-color: skyblue;
    height: 100vh;
    display: table;
    width: 100%;
}

.cover-inner {
    background-color: orange;
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}

.box {
    background-color: deepskyblue;
    width: 100px;
    height: 100px;
    padding: 20px 0;
    margin: 0 auto;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.