Replace deprecated media feature

[tysongach]

max-device-width is a deprecated media feature and throws an error in the CSS Validator:

Deprecated media feature max-device-width. For guidance, see the Deprecated Media Features section in the current Media Queries specification.

MDN also flags it as a deprecated feature: https://developer.mozilla.org/en-US/docs/Web/CSS/@media/device-width

max-width feels like a natural replacement and should behave the same in most browsers (if not all?).