<html>
<head>
<title>default box sizing (border-collapse: separate, standards mode)</title>
<style type="text/css">

body > div { float: left; clear: left; background: fuchsia; margin: 2px 0; }

div.inner {
  background: yellow;
}

</style>
</head>
<body>

<div style="width: 200px">
  <div style="background: blue; padding: 2px 3px 4px 5px">
    <div style="background: fuchsia; padding: 5px 8px 7px 10px">
      <div style="background: aqua; padding: 2px 3px 4px 5px">
        <div style="background: fuchsia; padding: 5px 7px 9px 11px">
          <div class="inner">x</div>
        </div>
      </div>
    </div>
  </div>
</div>

<div>
  <div style="background: blue; padding: 2px 3px 4px 5px">
    <div style="background: fuchsia; padding: 5px 8px 7px 10px">
      <div style="background: aqua; padding: 2px 3px 4px 5px">
        <div style="background: fuchsia; padding: 5px 7px 9px 11px">
          <div class="inner" style="width: 200px">x</div>
        </div>
      </div>
    </div>
  </div>
</div>

</body>
</html>