A system setting, surfaced to the web as the `prefers-reduced-motion` media query, by which a person asks software to cut animation that could unsettle them.
Gate the entrance animations behind `prefers-reduced-motion: no-preference` so they never play for someone who opted out.
Motion that delights most people can make others ill: a vestibular disorder turns a broad parallax sweep into a wave of nausea. Honoring the setting is not polish, it is consent. The honest pattern is to design the still version first and treat motion as a layer added on top, so removing it leaves the interface whole.