constant(). Beginning with Safari Technology Preview 41 and the iOS 11.2 beta, constant() has been removed and replaced with env(). You can use the CSS fallback mechanism to support both versions, if necessary, but should prefer env() going forward. env() ؔɺiOS 11Ͱconstant()ͱ͍͏໊લͰϦϦʔε͞Ε·ͨ͠ɻ Safari Technology Preview 41ͱiOS 11.2ϕʔλ൛͔Βɺconstant() আ͞Εɺenv() ʹஔ͖͑ΒΕ·ͨ͠ɻ CSSϑΥʔϧόοΫϝΧχ ζϜΛ༻ͯ͠ɺඞཁʹԠͯ྆͡ํͷόʔδϣϯΛαϙʔτͰ͖·͢ ͕ɺࠓޙenv() Λ༏ઌ͢Δඞཁ͕͋Γ·͢ɻ