<!DOCTYPE html>
<div id="scroller" style="overflow:scroll; position:relative; height:200px;">
  <div id="outer-hidden" style="position:absolute; overflow:hidden; width:300px; height:300px;">
    <div id="inner-hidden" style="opacity:0.5; width:100px; height: 100px; overflow:hidden">
      <div id="content" style="z-index:-1; position:absolute">hello</div>
    </div>
  </div>
</div>