The prefers-contrast media query is even better for accessibility [1]. It allows checking if the OS is in high contrast mode and adjust the colors appropriately.

I think the idea is to replace the Microsoft's proprietary -ms-high-contrast media query [2]. It means that prefers-contrast will work in Mac and Windows. Unfortunately, Safari Technology Preview 68 doesn't seem to implement it.

[1] https://drafts.csswg.org/mediaqueries-5/#prefers-contrast

[2] https://msdn.microsoft.com/library/Hh771830