| <!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, vertical centering</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="flags" content="" /> |
| <meta name="assert" content="An absolutely positioned non-replaced element's padding box (which is the area painted by background-color of the element) will be vertically centered within its containing block only if both 'margin-top' and 'margin-bottom' have equal values and if 'top' and 'bottom' have equal values. An absolutely positioned non-replaced element's margin box will be vertically centered within its containing block only if 'top' and 'bottom' have equal values." /> |
| <style type="text/css"> |
| #div1 |
| { |
| border: solid black; |
| height: 3in; |
| position: relative; |
| width: 3in; |
| } |
| div div |
| { |
| background: blue; |
| bottom: 0.5in; |
| height: 1in; |
| margin-bottom: auto; |
| margin-top: auto; |
| position: absolute; |
| top: 0.5in; |
| width: 100%; |
| } |
| |
| /* |
| |
| 0.5in : top |
| + |
| auto (solve): margin-top |
| + |
| 0 : border-top-width |
| + |
| 0 : padding-top |
| + |
| 1in : height |
| + |
| 0 : padding-bottom |
| + |
| 0 : border-bottom-width |
| + |
| auto (solve) : margin-bottom |
| + |
| 0.5in : bottom |
| ============= |
| 3.0in : height of containing block |
| |
| So, margin-bottom and margin-top must use 0.5in so that the equation gets balanced. |
| |
| */ |
| |
| |
| </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> |
