title: Css nth-child works strange
body: <p>I try to make a striped table. But when I try to use nth-child, it works really strange</p>
  
  <p>template:</p>
  
  <pre><code>...
  &lt;tr class="striped"&gt;...&lt;/tr&gt;
  &lt;tr class="more"&gt;...&lt;/tr&gt;
  ...
  </code></pre>
  
  <p>css:</p>
  
  <pre><code>tr.striped:nth-child(odd) {
      background-color : rgba($mainColor, .1);
  }
  </code></pre>
  
  <p>But all tr with striped class were colored. Maybe I miss some feature of specification?</p>