<!DOCTYPE html>

<html>
<head>
  <style type="text/css" media="screen">
    .box {
      display: inline-block;
      height: 120px;
      width: 300px;
      margin: 10px;
      border: 1px solid black;
      background-repeat: no-repeat;
      font-size: 12pt;
    }
    
    .em-units > .box {
      background-image: -webkit-linear-gradient(left, yellow, yellow 5em, green 5em);
      background-image: -moz-linear-gradient(left, yellow, yellow 5em, green 5em);
    }
    
    .indicator {
      background-color: black;
      height: 20px;
    }
  </style>
</head>
<body>

  <div class="em-units">
    <div id="box3" class="box"><div class="indicator" style="width: 5em;"></div></div>
    <div id="box4" class="box" style="font-size: 36pt"><div class="indicator" style="width: 5em"></div></div>
  </div>

</body>
</html>