155286 2016-03-09 19:30:38 -0800 CSS line-height computes ok, renders incorrectly 2023-10-02 18:12:29 -0700 1 1 1 Unclassified WebKit CSS Safari 9 Mac OS X 10.10 NEW https://bugs.webkit.org/show_bug.cgi?id=261212 InRadar P2 Major --- 1 tbredin zalan ahmad.saleem792 mmaxfield zalan oldest_to_newest 1172961 0 tbredin 2016-03-09 19:30:38 -0800 Unitless line heights appear to have an issue where the size of the element rendered to screen sometimes renders at a different size to the computed line-height. Take the following CSS: html { font-size: 125%; // 20px computed size } p { font-size: 1.5rem; // 30px computed size line-height: 1.33333333333; // 40px computed size } Here's a codepen that demonstrates the issue: http://codepen.io/tbredin/pen/ONNGmY In the inspector this reports the computed line-height as 40px. However the element only takes up 39px of space in the browser. Over long distances this can add up to a big error, is pretty severe (for example; vertical rhythm systems across multiple columns are busted really badly!) 1172992 1 zalan 2016-03-09 21:17:19 -0800 I bet it's one of the integral flooring we do for lineboxes. 1173000 2 mmaxfield 2016-03-09 21:33:26 -0800 (In reply to comment #1) > I bet it's one of the integral flooring we do for lineboxes. Yeah, this is because of the flooring. It would be great to get rid of that, but the compat risk worries me. 1176535 3 zalan 2016-03-19 15:46:55 -0700 rdar://problem/21713525 1981645 4 ahmad.saleem792 2023-10-01 15:59:52 -0700 @Alan - Can we mark this as duplicate to your IFC work to enable 'fractional' line height?