title: background image not displaying CSS
body: <p>I am trying to display a gradient background image but for some unfortunate reason, it doesn't display. this is my CSS and my HTML:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>html {
    background: url("static/pexels-gradienta-7130555.jpg") no-repeat center center fixed;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  
  &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;title&gt;My Website&lt;/title&gt;
    &lt;link rel="stylesheet" href="static/css/style.css"&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
    &lt;div class="background_image"&gt;
      foobar
    &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>