<!DOCTYPE HTML>
<html>
<head>
<style type="text/css">
.i {
  height: 10px;
  float: left;
}
</style>
</head>
<body>

<div style="width: 4px;">
  <div style="margin-left: 10px;">
    <div class="i"></div>
    <div class="i" style="border: 1px solid green">2</div>
  </div>
</div>

</body>
</html>