74131 2011-12-08 14:44:39 -0800 [CSS Regions] Incorrect margin-top result in regions with mixed widths 2022-07-13 09:29:04 -0700 1 1 1 Unclassified WebKit Layout and Rendering 528+ (Nightly build) All All RESOLVED WONTFIX AdobeTracked P2 Normal --- 119393 57312 1 stearns mihnea bfulgham donggwan.kim mihnea spena WebkitBugTracker oldest_to_newest 517814 0 118475 stearns 2011-12-08 14:44:39 -0800 Created attachment 118475 reftest If you have an element in a region with a percentage margin, and the region is followed by another region with a larger width, this affects the top margin display. If the element is displayed entirely within a single region its margins should only be affected by that single region. If an element spans regions the margins should be calculated for each segment using the local region dimensions. In the test file it appears as if the size and margin calculations are using the widest region in the flow, then moving and clipping for display in the first region. The computed dimensions are reported as 240px by 50px with a 30px margin, but the displayed dimensions are 160px by 50px with left and right margins of 20px and a top margin of 30px. For this testfile I'd expect the displayed dimensions but with an overall margin of 20px. 900391 1 michelangelo 2013-06-13 20:57:08 -0700 Still repros on today's nightly (r151543) 908398 2 spena 2013-07-15 08:00:11 -0700 Taking a look at this. 912723 3 spena 2013-07-30 02:31:14 -0700 I have been debugging this, and found that during the layout stage, the computed values of the margins end up being 30px (left, right and top). If you use the web inspector, those are the reported values. However, as Alan says in comment 0, the displayed margins are 20px. It is in the paint stage where the left and right margins get the 20px values they display, in the WebCore::RenderBox::borderBoxRectInRegion method. However, in that place the top margin is not updated. I talked to Mihnea and he warned me that since at this point margins are/can be collapsed (http://www.w3.org/TR/CSS2/box.html#collapsing-margins), it can be complicated / impossible to simply update the top-margin there. I am still trying to see if there's something we can do about the top margin (which doesn't break existing behaviour), but feel free to comment if you have some ideas or suggestions. My feeling is that trying to fix this behaviour so that we actually compute the correct margins in the layout stage would be quite complicated and would require many changes, but I might be missing something. 1883088 4 bfulgham 2022-07-13 09:29:04 -0700 CSS Regions were removed in Bug 174978. 118475 2011-12-08 14:44:39 -0800 2011-12-08 14:44:39 -0800 reftest top-margin.zip application/zip 1032 stearns UEsDBAoAAAAAAIhyiD8AAAAAAAAAAAAAAAALABAAdG9wLW1hcmdpbi9VWAwAGTjhTiA44U71ARQA UEsDBBQACAAIAG9yiD8AAAAAAAAAAAAAAAAuABAAdG9wLW1hcmdpbi90b3AtbWFyZ2luLWluLXJl Z2lvbnMtZXhwZWN0ZWQuaHRtbFVYDAAmOOFO8jfhTvUBFABlUUFuwyAQPDevWEXqsbXTKheX+BX9 ADYbg0q8CHCTqsrfuzar2lW5AMPszM6iUv7y2O6A13PEwdEI38ttXh1Fg7GBQ7hBIu8MdF73H2+/ hKsz2TbwUtfhtqIW3WAzlx038L14XHQc3Jg2JgVpDvXjP4XjH9mOrYdI02ieevIUm85PWJ5FPF9J hB9KZ69rY/edqiSsCu27RcgUxBzoDJmRWZBDc1hLk+e0uMBJXxB0Ws4ezxn0aCDOHUp9UlVgWeM+ ofc6pVOZZBnrBhZ2qyrGuEC2lbCXL+Age2H9AFBLBwjRcBGF3QAAAKIBAABQSwMEFAAIAAgAU3KI PwAAAAAAAAAAAAAAACUAEAB0b3AtbWFyZ2luL3RvcC1tYXJnaW4taW4tcmVnaW9ucy5odG1sVVgM ACE44U69N+FO9QEUAHVRQW7DIBA8N69YRerRtdMqF5f62BfkA9hgGwWzCHCcqsrfu9hUdlplL8Aw s8wszIcvLasdUL20Gif4nvexsknWZxWyCGfKBCwNH6T4pOP7TLotMic7heaRsHU4/BXGqtEJ6Uo4 2Ct41EpArXlzXgmTEqEv4bUo7HVFe6m6PpDsuIGTkYG7Thm/cbIg5aF4/tfheNe2pqc7h6MRWYMa XVnrUd6lDBOmxk+Ls7fV2G3H8jRIZqtTLyGgTY8DthAIiQ0pNIXtcdSUVs6wp8kA9/NeyzYANwJc dJj0nuWW2gp1gUZz7z/iVJcP24CJW7GcMKKnZSXsl1/aVw+vgBL+Xv8AUEsHCD/m1LEBAQAAFwIA AFBLAQIVAwoAAAAAAIhyiD8AAAAAAAAAAAAAAAALAAwAAAAAAAAAAEDtQQAAAAB0b3AtbWFyZ2lu L1VYCAAZOOFOIDjhTlBLAQIVAxQACAAIAG9yiD/RcBGF3QAAAKIBAAAuAAwAAAAAAAAAAECkgTkA AAB0b3AtbWFyZ2luL3RvcC1tYXJnaW4taW4tcmVnaW9ucy1leHBlY3RlZC5odG1sVVgIACY44U7y N+FOUEsBAhUDFAAIAAgAU3KIPz/m1LEBAQAAFwIAACUADAAAAAAAAAAAQKSBggEAAHRvcC1tYXJn aW4vdG9wLW1hcmdpbi1pbi1yZWdpb25zLmh0bWxVWAgAITjhTr034U5QSwUGAAAAAAMAAwAMAQAA 5gIAAAAA