title: Apply style to element, only if a certain element exists next to it
body: <p>I'm using the <code>&lt;section&gt;</code> tag on several pages, but on ONE page I'm using an <code>&lt;aside&gt;</code> tag that is preceded by the <code>&lt;section&gt;</code> tag.</p>
  
  <p>In the case that I have a <code>&lt;section&gt;</code> immediately followed by an <code>&lt;aside&gt;</code>, I would like to apply a width to both and have the section float left, and the aside float right.</p>
  
  <p>Basically, if I have a <code>&lt;section&gt;</code> and <code>&lt;aside&gt;</code> I want the style to work like this:</p>
  
  <pre><code>section {
      width: 500px;
      float: left;
      padding: 8px;
  }
  
  aside {
      padding:8px; 
      width:400px;
      float:right;
  }
  </code></pre>
  
  <p>If I only have the <code>&lt;section&gt;</code> I want it to be like:</p>
  
  <pre><code>section {
      padding: 8px;
  }
  </code></pre>
  
  <p>Is there a way I can do this with either a conditional statement in CSS3, or a pseudo-class, without having to use JavaScript, custom classes, or separate CSS files?</p>