testing/web-platform/tests/css/css-backgrounds/reference/background-size-043-ref.html
<!DOCTYPE html>
<title>CSS Reftest Reference</title>
<link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
<style>
div#black-walls
{
border: solid 40px;
border-color: transparent black;
height: 400px;
width: 400px;
}
div#inner-orange
{
background-color: orange;
border: blue solid 16px;
height: 368px; /* 400px - 2 * 16px == 368px */
margin: 0px auto;
/* the orange block is horizontally centered inside div#black-walls */
width: 168px; /* 200px - 2 * 16px == 168px */
}
</style>
<div id="black-walls"><div id="inner-orange"></div></div>
