<style type="text/css">
  .box { width: 200px; height: 200px; display: inline-block; }
  #brown { background-color: brown; margin-right: 100px; }
  #green { background-color: green; margin-left: 100px; }
</style>
<div id="brown" class="box"/><div id="green" class="box"/>

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