<!DOCTYPE html>
<html>
<head>
<title>Test</title>
<style>
html,
body {
height: 100%;
}
.container {
width: 100%;
height: 100%;
display: flex;
flex-direction: column;
background-color: black;
}
.smaller {
height: 70%;
width: 70%;
background-color: green;
}
.superinner {
height: 100%;
width: 100%;
margin-top: 20px;
margin-bottom: 20px;
margin-left: 20px;
margin-right: 20px;
background-color: red;
justify-content: center;
align-items: center;
flex-direction: column;
}
</style>
</head>
<body>
<div class="container">
<div class="smaller">
<div class="superinner">
<h1>Hello World</h1>
<p>This is a test</p>
</div>
</div>
</div>
</body>
</html>