title: stick element to top of page until next element of that type appears
body: <p>I'm having a hard time giving a good description of this, but bear with me:</p>
  
  <p>If I have a page structed like this</p>
  
  <pre><code>&lt;h2&gt;Chapter 1&lt;/h2&gt;
  &lt;p&gt;Lots of text that has mutiple screen worths of content&lt;/p&gt;
  &lt;h2&gt;Chapter 2&lt;/h2&gt;
  &lt;p&gt;Lots of text...&lt;/p&gt;
  </code></pre>
  
  <p>I'd like to have "Chapter 1" absolutely positioned or whatever at the top of the page until the user scrolls down to where "Chapter 2" starts, at which point now "Chapter 2" is displayed at the top of the page.</p>
  
  <p>We can add wrapper classes and divs if needed. Solutions that use JQuery would be great.</p>