css/css-sizing/box-sizing-border-box-001.xht

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title>CSS Test: Box Sizing - Border-Box with specified width</title>
  <link rel="author" title="Scott Johnson" href="mailto:sjohnson@mozilla.com" />
  <link rel="help" href="https://drafts.csswg.org/css-sizing-3/#box-sizing" />
  <link rel="match" href="box-sizing-border-box-001-ref.xht" />
  <meta name="assert" content="box-sizing: border-box should make the element's (percentage) width be the distance from the left border edge to the right border edge." />
  <style type="text/css"><![CDATA[
    .container {
      width: 300px;
      border: 2px solid black;
      position: absolute;
      left: 25px;
      top: 25px;
      background-color: red;
    }

    .box-sized {
      box-sizing: border-box;
      width: 50%;
      z-index: 1;
      float: left;
      border: 5px solid black;
    }

    #one {
      background-color: green;
    }

    #two {
      background-color: blue;
    }
  ]]></style>
 </head>
 <body>
   The two divs should be side-by-side, not one on top of another. No red should be visible.
   <br />
   <div class="container">
     <div class="box-sized" id="one">LEFT HALF</div>
     <div class="box-sized" id="two">RIGHT HALF</div>
   </div>
 </body>
</html>