<!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: Absolutely positioned, non-replaced elements, 'margin-top' and 'margin-bottom' set to '0'</title>
<link rel="author" title="Microsoft" href="http://www.microsoft.com/" />
<link rel="reviewer" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/" /> <!-- 2012-08-31 -->
<link rel="help" href="http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-height" />
<link rel="match" href="absolute-non-replaced-height-003-ref.xht" />
<meta name="assert" content="The 'auto' values for 'margin-top' and 'margin-bottom' are set to '0', when 'top' is 'auto' and 'height' and 'bottom' are not 'auto'." />
<style type="text/css">
#div1
{
border: solid black;
height: 3in;
position: relative;
width: 3in;
}
div div
{
background: blue;
bottom: 1in;
height: 1in;
margin-bottom: auto;
margin-top: auto;
position: absolute;
top: auto;
width: 100%;
}
/*
auto (to solve) : top
+
auto (to solve): margin-top
+
0 : border-top-width
+
0 : padding-top
+
1in : height
+
0 : padding-bottom
+
0 : border-bottom-width
+
auto (to solve): margin-bottom
+
1in : bottom
=============
3in : height of containing block
"
'top' is 'auto', 'height' and 'bottom' are not 'auto',
then set 'auto' values for 'margin-top' and 'margin-bottom' to 0,
and solve for 'top'
"
so this brings:
auto (to solve) : top
+
0 (set): margin-top
+
0 : border-top-width
+
0 : padding-top
+
1in : height
+
0 : padding-bottom
+
0 : border-bottom-width
+
0 (set): margin-bottom
+
1in : bottom
=============
3in : height of containing block
So, top must use 1in in order to balance the equation
*/
</style>
</head>
<body>
<p>Test passes if a blue rectangle is <strong>vertically centered</strong> in an hollow black square.</p>
<div id="div1">
<div></div>
</div>
</body>
</html>
Codebase Browser
chromium