The mind must be given relaxation; it will arise better and keener after resting. As rich fields must not be forced-for their productiveness, the have no rest, will quickly exhaust them constantlabor will break the vigor of the mind, but if it is released and relaxed a little while, it will recover its powers
Seneca

image-set()

The image-set() CSS functional notation is a method of letting the browser pick the most appropriate CSS image from a given set, primarily for high pixel density screens.
image-set() css reference