Restrained
A quality of design that uses far less expression than it could — color, motion, and emphasis held in reserve rather than spent.
Example usage
“The launch page is restrained: one typeface, one accent, and a single animation where competitors would use ten.”
Editor’s note
Restraint is only legible when capability is evident — a plain page by a limited designer is just plain; the same page by a capable one is restrained. The practical method: build the louder version, then pull it back until removing anything more would cost clarity. What survives is the design.