233820 2021-12-03 09:26:25 -0800 Implement @custom-media from Media Queries Level 5 2026-04-01 21:04:43 -0700 1 1 1 Unclassified WebKit CSS Safari Technology Preview All All NEW https://www.w3.org/TR/mediaqueries-5/#custom-mq InRadar P2 Enhancement --- 1 afrehner.work webkit-unassigned 50167214 nileshprajapati r_a_m_i sebastianzartner webkit-bug-importer woodlxf00 oldest_to_newest 1820171 0 afrehner.work 2021-12-03 09:26:25 -0800 https://www.w3.org/TR/mediaqueries-5/#custom-mq Apologies if there is an issue already for this; I searched and was unable to find anything, but let me know if I missed it. Thank you. 1822760 1 webkit-bug-importer 2021-12-10 09:27:39 -0800 <rdar://problem/86325417> 2167972 2 r_a_m_i 2025-12-23 10:48:11 -0800 Firefox 146 added support for `@custom-media` under a flag. 2196137 3 50167214 2026-04-01 21:04:43 -0700 To be precise, it’s Firefox 148. See https://github.com/mdn/content/issues/42201#issuecomment-3625571010