title: Scroll down animate or trigger block
body: <p>I'm trying to recreate something similar to the following:
  <a href="https://www.apple.com/uk/ipad-mini/design/" rel="nofollow">https://www.apple.com/uk/ipad-mini/design/</a></p>
  
  <p>When you scroll down on the page it seems to understand that a certain area, when viewed, triggers an animated element. I'm trying to base next steps on this but unsure what to start in. I understand elements of HTML, CSS, DIV Tags and potentially switching on a hidden block when viewed might be the answer. But need advice of the simple trigger element. Java? PHP? CSS?</p>
  
  <p>So when the user scrolls down maybe 30% a hidden element appears or animates. I would animate in adobe edge if that helps. </p>
  
  <p>Any good?</p>