title: magnetic div: fixed div inside absolute positioned div
body: <p>I have the following page:</p>
  
  <p><a href="https://dl.dropbox.com/s/tilydgoo7jcsjbu/Index.html">[LINK]</a></p>
  
  <p>The page is designed to be scrolled horizontally, so that a series of divs (black bordered ones) appear in a row.</p>
  
  <p>Now, I the smaller divs inside (red ones) to behave so that they never go outside the parent div but at the same time, while scrolling the page, I want them to move inside the parent div like if they were fixed-positioned.</p>
  
  <p>I'll explain myself with a diagram. I want my divs to behave like this:</p>
  
  <p><a href="https://dl.dropbox.com/s/egipbbeul5b4y8g/IMG.gif">[LINK]</a></p>
  
  <p>Anyone can help? Thanks for your time!</p>