title: How to use Bootstrap affix with large sidebar?
body: <p>My sidebar is large and doesn't fit in my window. When I scroll down and reach bottom of sidebar, it sticks to window bottom and goes down with content, and when I scroll up, sidebar must scroll to its top, stick to window top, and go to the top of page.</p>
  
  <p>I tried to use: </p>
  
  <pre><code>&lt;aside data-spy="affix" data-offset-top="590"&gt;
  ...
  &lt;/aside&gt;
  </code></pre>
  
  <p>but it sticks to bottom, and when I scroll up, it stays fixed until sidebar reaches top of page.</p>
  
  <p>What could be the issue?</p>