<!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 Multi-column Layout Test: nested multicolumns and vertical margin (complex)</title> <link rel="author" title="Opera Software ASA" href="http://www.opera.com/" /> <link rel="reviewer" title="GĂ©rard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/" /> <!-- 2013-08-14 --> <link rel="help" href="http://www.w3.org/TR/css3-multicol/#the-multi-column-model" title="2. The multi-column model" /> <link rel="match" href="multicol-nested-margin-002-ref.xht" /> <meta name="flags" content="ahem" /> <meta name="assert" content="This test checks that when an inner nested multi-column element is preceded by a soft column break (caused by an unforced column-break), then the used margin-top of such inner nested multi-column element is '0'." /> <!-- More info: Re: [css3-multicol] vertical margins rendering in nested multi-columns http://lists.w3.org/Archives/Public/www-style/2013Aug/0146.html --> <link rel="stylesheet" type="text/css" href="/fonts/ahem.css" /> <style type="text/css"><![CDATA[ body {margin: 0;} body > div { background-color: yellow; font: 1.25em/1 Ahem; width: 41em; /* This test requires a viewport width of 820px */ } div { color: yellow; font: inherit; orphans: 1; widows: 1; column-count: 3; column-gap: 1em; } div div {margin: 0em 1em;} div div:last-child { color: blue; margin: 1em; } /* N == 3; W == max(0, (available-width - ((N - 1) * column-gap)) / N); W == max(0, (41em - ((3 - 1) * 1em)) / 3); W == max(0, (41em - (2 * 1em)) / 3); W == max(0, (41em - 2em) / 3); W == max(0, 39em / 3); W == max(0, 13em); W == 13em; The height of column rule depends on number of line boxes in each outer column box which depends on number of line boxes in each inner column box. So: 13em : width of each outer column box - 2em : horizontal margin of each div inside ======= 11em : width of each inner multi-column elements N == 3; W == max(0, (available-width - ((N - 1) * column-gap)) / N); W == max(0, (11em - ((3 - 1) * 1em)) / 3); W == max(0, (11em - (2 * 1em)) / 3); W == max(0, (11em - 2em) / 3); W == max(0, 9em / 3); W == max(0, 3em); W == 3em; So, each duo of 'a', 'm' and 'x' should fill one and only 1 line box. There are 15 'a' duos and 15 'm' duos; therefore, the 3 inner column boxes of each first 2 inner multi-column elements should use 5 line boxes. The 1st column box of last inner multi-column (the blue one with 'x' duos) should have 'x1', 'x2' and 'x3' duos filling 3 line boxes. The 2nd column box of last inner multi-column should have 'x4', 'x5' and 'x6' duos filling 3 line boxes. The 3rd column box of the last inner multi-column should have 'x7' and 'x8' duos filling 2 line boxes. */ ]]></style> </head> <body> <div> <div> a1 a2 a3 a4 a5 a6 a7 a8 a9 a0 a1 a2 a3 a4 a5 </div> <div> m1 m2 m3 m4 m5 m6 m7 m8 m9 m0 m1 m2 m3 m4 m5 </div> <div> x1 x2 x3 x4 x5 x6 x7 x8 </div> </div> </body> </html>