mozilla-release/gfx/tests/reftest/1451168-ref.html

<!DOCTYPE html>
<html>
<head>
  <style type="text/css">
html {
    height:100%;
    margin:0;
    padding: 0;
}
body {
    height:100%;
    margin: 0;
    padding: 0;
    overflow:hidden;
    position:relative;
    left:0;
}
nav {
    display:block;
    position:absolute;
    top:0;
    left:0;
    bottom:auto;
    width:280px;
    height:100%;
    z-index:1000;
}

.nav-menu-inner-container {
    position:relative;
    height:100%;
}

.nav-menu-scroll-pane {
    bottom:100px;
    overflow-y:scroll;
    position:absolute;
    top:0;
    width:254px
}
  </style>
</head>

<body>
<nav class="moz-global-nav-drawer">
  <div class="nav-menu-inner-container">
    <div class="nav-menu-scroll-pane">
      <div style="height: 5000px">
        Scroll here and look for the scrollbar
      </div>
    </div>
  </div>
</nav>
</body></html>