title: scroll-behavior smooth with anchor tag making no difference
body: <p>I'm trying to achieve a smooth scroll when the anchor link is clicked, but at the moment I'm still getting the quick jump to #content and I can't work out where I'm going wrong. </p>
  
  <p>HTML: </p>
  
  <pre><code>&lt;body class="home"&gt;
    &lt;section id="cover-section" class="section cover"&gt;
      &lt;div class="cover-inner content"&gt;
        &lt;h1 class="title"&gt;&lt;span class="title-inner"&gt;TITLE&lt;/span&gt;&lt;/h1&gt;
        &lt;p class="byline"&gt;Some text here&lt;/p&gt;
        &lt;a class='section-jump' href='#content'&gt;&lt;/a&gt;
      &lt;/div&gt;
    &lt;/section&gt;
    &lt;section class="section content"&gt;
      &lt;a id='content' href="https://github.community/t5"&gt;&lt;img src="logo.png"
          alt="Logo image" title="Logo"&gt;&lt;/a&gt;
  </code></pre>
  
  <p>CSS: </p>
  
  <pre><code>.section-jump {
    content: '';
    position: absolute;
    left: 50%;
    bottom: 1em;
    border: 0.5em solid white;
    width: 0;
    height: 0;
    border-left-color: transparent;
    border-right-color: transparent;
    border-bottom-color: transparent;
  }
  
  .section.content {
    height: 100vh;
    scroll-behavior: smooth;
  }
  </code></pre>
  
  <p>Browser information: 
  Chrome version 69.0.3497.100
  Also tested in Safari 12.0</p>