unit-vh-vw-overflow-auto-ref-iframe.html

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<style>

  body { overflow: hidden }

  div {

    width: 10px;

    height: 10px;

    background-color: #d64203;

</style>

<body>

  <div id="a"></div>

  <div id="b"></div>

  <div id="c"></div>

  <div id="d"></div>

  <!--

  Deliberately make the scrollbars appear to ensure that with 'overflow: auto'

  viewport units are calculated as if the scrollbars are _not_ there.

-->

  <div style="width: 500px; height: 500px; background-color: black">

</body>

<script>

  // client{Width, Height} consist of the area _inside_ the scrollbars, so we need

  // to calculate these units with 'overflow: hidden' set to ensure that there are

  // no scrollbars. This reflects the fact that with 'overflow: auto' set, viewport

  // units are sized without taking the scrollbars into account.

  var vw = 0.01 * document.body.clientWidth;

  var vh = 0.01 * document.body.clientHeight;

  var vmin = Math.min(vw, vh);

  var vmax = Math.max(vw, vh);

  document.body.style.overflow = "auto";

  document.getElementById('a').style.width = (50 * vw) + "px";

  document.getElementById('b').style.height = (25 * vh) + "px";

  document.getElementById('c').style.width = (35 * vmin) + "px";

  document.getElementById('d').style.height = (25 * vmax) + "px";

</script>