title: Linear-gradient as body background
body: <p>I am trying to make a body background as a linear-gradient, but it doesn't work. However, when i am setting a solid color it's ok (e. g. background: red;) Here is some code:</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>* {
    margin: 0;
    padding: 0;
  }
  
  body {
    width: 100%;
    height: 100%;
    /* background: red;*/
    background: linear-gradient(#648880, #293f50);
    margin: auto;
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    right: 0;
  }
  
  #chatbox {
    background: DarkKhaki;
    padding: 10px;
    width: 400px;
    height: 200px;
    margin: auto;
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    right: 0;
  }
  
  #user_msg {
    font: 24px Tahoma;
    position: absolute;
    bottom: 10px;
    width: 300px;
    height: 30px;
  }
  
  #send_button {
    height: 30px;
    position: absolute;
    bottom: 10px;
    right: 10px;
  }
  
  #chatbox {
    border: 1px solid gray;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"&gt;
    &lt;meta http-equiv="X-UA-Compatible" content="ie=edge"&gt;
  
  &lt;/head&gt;
  
  &lt;body&gt;
  
    &lt;div id="chatbox"&gt;
      &lt;div id="msgs"&gt;
        Ai says:&lt;br&gt; You say:
      &lt;/div&gt;
      &lt;form&gt;
        &lt;input id="user_msg" type="text"&gt;
        &lt;input id="send_button" type="submit" value="send"&gt;
      &lt;/form&gt;
    &lt;/div&gt;
  &lt;/body&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>What's the problem here?</p>