<!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: transparency of margin area and background-color</title> <link rel="author" title="GĂ©rard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/" /> <link rel="help" href="http://www.w3.org/TR/CSS21/box.html#mpb-examples" title="8.2 Example of margins, padding, and borders" /> <link rel="help" href="http://www.w3.org/TR/CSS21/colors.html#background" title="14.2 The background" /> <link rel="match" href="../reference/ref-filled-green-100px-square.xht" /> <meta content="The margin area of an element is always transparent. The background-color of an element never paints its own margin area. The background-color of an element only paints its own border area (if any), its own padding area (if any) and its own content area (if any). Therefore the background-color of the content area (and of the padding area, if any, and of the border area, if any) of a parent element shines through the margin area of its child. In this test, div#parent is painted green and is 100px wide by 98px tall; its sole child has 98px vertical margins and 100px horizontal margins which are transparent and through which we can see the background color of its parent." name="assert" /> <style type="text/css"><![CDATA[ div#parent { background-color: green; border-top: green solid 2px; /* This border-top's sole purpose is to prevent margin collapsing between itself and the p's margin-bottom */ height: 98px; width: 100px; } div#child { background-color: red; margin: 49px 50px; } ]]></style> </head> <body> <p>Test passes if there is a filled green square and <strong>no red</strong>.</p> <div id="parent"> <div id="child"></div> </div> </body> </html>