299836 2025-09-29 18:02:05 -0700 [css-multicol-1] column-count: 1 should create a multi-column container 2025-11-25 06:01:21 -0800 1 1 1 Unclassified WebKit Layout and Rendering WebKit Local Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 289743 1 fantasai.bugs fantasai.bugs bfulgham kiet.ho murakami simon.fraser webkit-bug-importer zalan oldest_to_newest 2147015 0 fantasai.bugs 2025-09-29 18:02:05 -0700 Per spec, a non-auto value of column-count creates a multicol container, see https://www.w3.org/TR/css-multicol-1/#the-multi-column-model https://www.w3.org/TR/css-multicol-1/#cc "An element whose column-width or column-count property is not auto establishes a multi-column container (or multicol container for short), and therefore acts as a container for multi-column layout." This is noticeable when the element has a fixed height: in this case the content should be fragmented into columns that overflow in the inline axis. See this testcase in e.g. WebKit vs Firefox: <div style="column-count: 1; height: 1.5em; border: solid;">1<br>2<br>3</div> https://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cdiv%20style%3D%22column-count%3A%201%3B%20height%3A%201.5em%3B%20border%3A%20solid%3B%22%3E1%3Cbr%3E2%3Cbr%3E3%3C%2Fdiv%3E 2147016 1 webkit-bug-importer 2025-09-29 18:02:26 -0700 <rdar://problem/161611444> 2147026 2 fantasai.bugs 2025-09-29 18:49:17 -0700 Pull request: https://github.com/WebKit/WebKit/pull/51536 2147035 3 fantasai.bugs 2025-09-29 19:22:51 -0700 This blocks passing anchor-position-multicol-008, so marking as a WPT dependency. 2147354 4 ews-feeder 2025-09-30 16:58:47 -0700 Committed 300787@main (e10b646accd3): <https://commits.webkit.org/300787@main> Reviewed commits have been landed. Closing PR #51536 and removing active labels.