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<head>
<title>CSS Test: blur computation for box-shadow</title>
<meta name="assert" content="the resulting shadow must approximate (with each pixel being within 5% of its expected value) the image that would be generated by applying to the shadow a Gaussian blur with a standard deviation equal to half the blur radius" />
<style type="text/css">
div.stripecontainer {
width: 600px;
height: 30px;
border: medium solid blue;
}
div.refimage, div.blurcontainer {
width: 600px;
height: 10px;
}
div.refimage img {
display: block;
}
div.blurcontainer { position: relative; overflow: hidden }
div.blur {
position: absolute;
width: 2000px;
height: 2010px;
top: -1000px; /* places 1000px both above and below container */
left: -2000px; /* places right edge at left of container */
box-shadow: 300px 0 100px black;
}
</style>
</head>
<body>
<p>The following test should contain three grayscale stripes, each 10
pixels tall, with no space between them, but all enclosed within a
blue border. At all points, the middle stripe must be <strong>the
same color as or darker than</strong> the top stripe, and <strong>the
same color as or lighter than</strong> the bottom stripe. (This tests
that the blurring algorithm produces results within 5% of a Gaussian
blur.)</p>
<div class="stripecontainer">
<div class="refimage"><img height="10" width="600" src="support/box-shadow-blur-definition-001-light-bound.png" alt="[reference stripe image]" /></div>
<div class="blurcontainer"><div class="blur"></div></div>
<div class="refimage"><img height="10" width="600" src="support/box-shadow-blur-definition-001-dark-bound.png" alt="[reference stripe image]" /></div>
</div>
</body>
</html>