<html>
<head>
<style>
  div.a  {
    -moz-column-count: 2;
    float: left;
    background: lightblue;
  }
  div.b  {}
  div.c  {
    float: left;
    height: 23px;
    width:  10px;
    background: orange;
  }
  div.d  {
    float: left;
    height: 22px;
    width:  10px;
    background: green;
  }
  div.e  {
    clear: left;
  }
</style>
</head>
<body
   ><div class="a"
       ><div class="b"
           ><div class="c"
           ></div
           ><div class="d"
           ></div
           ><div class="e"
           ></div
       > <!-- whitespace --></div
   ></div
></body>
</html>