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jwinterm
1a66e2217a
The splash now runs its water-ripple enter 1.5s after paint instead of waiting
to be clicked. A click, scroll, or arrow key still fast-forwards it, and the
once-per-session flag and reduced-motion skip are unchanged.
Auto-advancing on its own would have cost the Lighthouse score badly: mobile
100 -> 73, desktop 97 -> 73. The cause was not LCP, which never moved. It was
CLS going 0 -> 1.0, and the reason is worth writing down.
The splash was `relative min-h-[100svh]`, a full viewport of height IN document
flow, and only became `fixed` on the way out. Dismissing it therefore pulled a
whole screen out of the flow and shoved the hero up: a layout shift of almost
exactly 1.0. Clicking hid that from CLS, because shifts within 500ms of user
input are excused. Nothing else did.
Which means this was already shipping to real people. Visitors with
prefers-reduced-motion, and anyone returning within a session, never click, so
they took the shift in full: production measured 74 on mobile with CLS 1.0.
The click-gate was masking a live bug, not preventing one.
The splash is now a fixed overlay from its first paint, so it is never in flow
and dismissing it cannot reflow anything. Measured on a local production build:
before -> after
mobile, auto-advance 73 -> 98 (CLS 1.0 -> 0.005)
mobile, reduced-motion 74 -> 98 (CLS 1.0 -> 0.005)
desktop, auto-advance 73 -> 98 (CLS 0.702 -> 0.011)
Mobile gives up 2 points against today's click-gated 100, entirely in Speed
Index (1.9s -> 4.4s), which is the unavoidable cost of holding a cover at all.
Desktop ends up ahead of where it started. The hold is one constant if you want
a different beat.
The scroll-past-to-dismiss IntersectionObserver is gone: an overlay never
leaves the viewport, so it could not fire. Scroll intent still enters, via the
wheel/touch/key handlers already in the splash, and the shell now locks page
scroll while the cover is up.