title: :after and :before pseudo-element selectors in Sass
body: <p>How can I use the :before and :after pseudo-element selectors following the syntax of Sass or, alternatively, SCSS? Like this:</p>
  
  <pre><code>p
    margin: 2em auto
    &gt; a
      color: red
    :before
      content: ""
    :after
      content: "* * *"
  </code></pre>
  
  <p>Of course, the above fails.</p>