<!DOCTYPE html>
<html>
  <head>
    <style>
      span.b { display: inline-block; height: 20px; }
    </style>
  </head>
  <body>
    <div>
      <span style="background: url(blue-8x20.png);">
        <span class="b" style="width: 8px"></span>
      </span>
    </div>
    <div>
      <span style="background: url(blue-8x20-green-8x20.png);">
        <span class="b" style="width: 16px"></span>
      </span>
    </div>
    <div>
      <span style="background: url(green-8x20.png);">
        <span class="b" style="width: 8px"></span>
      </span>
    </div>
  </body>
</html>