TinyMCE AutoResize issue with html and body height 100%

<!DOCTYPE html>
<html>

  <head>
    <script data-require="tinymce@*" data-semver="4.3.3" src="https://cdn.tinymce.com/4/tinymce.min.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
  </head>

  <body>
    <h1>Hello TinyMCE!</h1>
    <textarea></textarea>
  </body>

</html>

tinymce.init({
  selector: 'textarea',  // change this value according to your HTML
  plugins: 'autoresize',
  content_css: 'editor.css'
});

/* Styles go here */

When using the TinyMCE plugin AutoResize while html and body are set to 100%
on the editor window, the editor size keeps on growing after getting focus.

html, body {
  height: 100%;
}