287918 2025-02-18 17:22:04 -0800 random() with viewport units changes on every layout 2025-02-19 09:16:22 -0800 1 1 1 Unclassified WebKit CSS Other Unspecified Unspecified RESOLVED WORKSFORME InRadar P2 Normal --- 1 simon.fraser webkit-unassigned koivisto ntim sam simon.fraser webkit-bug-importer oldest_to_newest 2095693 0 474283 simon.fraser 2025-02-18 17:22:04 -0800 Created attachment 474283 Test case Load the attached testcase, with `random()` enabled, and resize the window. Note that the stars move around with every resize. This is surprising. 2095694 1 webkit-bug-importer 2025-02-18 17:22:35 -0800 <rdar://problem/145102437> 2095883 2 sam 2025-02-19 08:48:32 -0800 I believe this is behaving correctly per the current spec as the random caching keys are calculated from the "used values", so each time the window is resized, the used values for the viewport units change, and thus a new random value is selected. See https://drafts.csswg.org/css-values-5/#random-caching Whether this behavior is good / expected is another story. WebKit is the first to implement, so feedback to the editors on this makes sense to me. 2095887 3 ntim 2025-02-19 09:16:22 -0800 I filed https://github.com/w3c/csswg-drafts/issues/11747 474283 2025-02-18 17:22:04 -0800 2025-02-18 17:22:04 -0800 Test case random-starfield.html text/html 948 simon.fraser PCFET0NUWVBFIGh0bWw+CjxodG1sPgo8aGVhZD4KICAgIDxtZXRhIG5hbWU9InZpZXdwb3J0IiBj b250ZW50PSJ3aWR0aD1kZXZpY2Utd2lkdGgsIGluaXRpYWwtc2NhbGU9MSwgc2hyaW5rLXRvLWZp dD1ubyI+CiAgICA8dGl0bGU+PC90aXRsZT4KICAgIDxzdHlsZT4KICAgICAgICA6cm9vdCB7CiAg ICAgICAgICAgIGJhY2tncm91bmQtY29sb3I6ICMxMTE7CiAgICAgICAgfQogICAgICAgIC5zdGFy IHsKICAgICAgICAgICAgcG9zaXRpb246IGFic29sdXRlOwogICAgICAgICAgICBsZWZ0OiByYW5k b20ocGVyLWVsZW1lbnQsIDB2dywgMTAwdncpOwogICAgICAgICAgICB0b3A6IHJhbmRvbShwZXIt ZWxlbWVudCwgMHZoLCAxMDB2aCk7CiAgICAgICAgICAgIHdpZHRoOiByYW5kb20ocGVyLWVsZW1l bnQsIDFweCwgNXB4KTsKICAgICAgICAgICAgaGVpZ2h0OiByYW5kb20ocGVyLWVsZW1lbnQsIDFw eCwgNXB4KTsKICAgICAgICAgICAgYm9yZGVyLXJhZGl1czogNTAlOwogICAgICAgICAgICBiYWNr Z3JvdW5kLWNvbG9yOiB3aGl0ZTsKICAgICAgICB9CiAgICA8L3N0eWxlPgogICAgPHNjcmlwdD4K ICAgICAgICB3aW5kb3cuYWRkRXZlbnRMaXN0ZW5lcignbG9hZCcsICgpID0+IHsKICAgICAgICAg ICAgY29uc3QgbnVtU3RhcnMgPSAxMDA7CiAgICAgICAgICAgIAogICAgICAgICAgICBmb3IgKGxl dCBpID0gMDsgaSA8IG51bVN0YXJzOyArK2kpIHsKICAgICAgICAgICAgICAgIGNvbnN0IHN0YXIg PSBkb2N1bWVudC5jcmVhdGVFbGVtZW50KCdkaXYnKTsKICAgICAgICAgICAgICAgIHN0YXIuY2xh c3NOYW1lID0gJ3N0YXInOwoKICAgICAgICAgICAgICAgIGRvY3VtZW50LmJvZHkuYXBwZW5kQ2hp bGQoc3Rhcik7CiAgICAgICAgICAgIH0KICAgICAgICB9LCBmYWxzZSk7CiAgICA8L3NjcmlwdD4K PC9oZWFkPgo8Ym9keT4KICAgIAo8L2JvZHk+CjwvaHRtbD4K