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

animation-duration

The animation-duration CSS property sets the length of time that an animation takes to complete one cycle.
animation-duration css reference