<!DOCTYPE html>
<style>
  body, html {
    height: 100%;
    width: 100%;
  }
  #spacer {
    width: 1500px;
    height: 1500px;
    background-color: red;
  }
</style>
<body>
  <p>This page is scrollable.</p>
  <div id="spacer"></div>
</body>
