title: Flex footer does not move with dropdown menu
body: <p>I'm having an issue with a dropdown menu expanding the page with a scrollbar, but the footer at the bottom of the page does not move down.</p>
  
  <p>Example JSFiddle: <a href="https://jsfiddle.net/fmoctax3/" rel="nofollow noreferrer">https://jsfiddle.net/fmoctax3/</a></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-js lang-js prettyprint-override"><code>$('.ui.dropdown').dropdown();</code></pre>
  <pre class="snippet-code-css lang-css prettyprint-override"><code>html,
  body {
    height: 100vh;
    min-height: 100%;
    margin: 0;
  }
  
  body {
    display: flex;
    flex-flow: column;
  }
  
  .main {
    flex: 1 1 auto;
    background: green;
  }
  
  .footer {
    background: orange;
  }
  
  .ui.dropdown {
    margin-left: 50vw;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link href="https://cdnjs.cloudflare.com/ajax/libs/semantic-ui/2.2.10/semantic.min.css" rel="stylesheet"/&gt;
  &lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/semantic-ui/2.2.10/semantic.min.js"&gt;&lt;/script&gt;
  
  
  &lt;div class="main"&gt;
    &lt;div class="ui floating dropdown"&gt;
      &lt;label class="ui button"&gt;Dropdown&lt;/label&gt;
      &lt;i class="dropdown icon"&gt;&lt;/i&gt;
      &lt;div class="menu"&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
        &lt;div class="item"&gt;Item&lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  &lt;div class="footer"&gt;
    stuff&lt;br&gt;stuff&lt;br&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Why is this happening and how do I get the footer and main to expand as well?</p>