Opening a gallery with a dark theme briefly painted a white background
between the initial HTML render and React applying the per-event theme.
The HTML shipped with no theme info, so the first paint used the
default (#fafafa) before /gallery/:slug/info resolved.
Two-part fix.
1. Inline bootstrap script in index.html runs synchronously before React
mounts. Reads the URL, looks up a per-slug background colour from
localStorage (gallery-theme-bg-<slug>), and applies it to
documentElement immediately. Falls back to #171717 when no cache
exists and the OS prefers dark, so first visits with dark OS still
land on a dark background.
2. ThemeContext.applyTheme writes the resolved background to
localStorage keyed by slug whenever a gallery theme loads. Revisits
then hit the bootstrap cache and never see a flash.
Added a 200ms transition on html.background-color so the rare
cache→API drift (e.g. theme palette changed admin-side since last
visit) is a smooth fade instead of a snap.
Limitation: first visit on a light-OS device to a dark gallery still
flashes once. Killing that case requires a server-rendered theme hint,
out of scope for an SPA bootstrap fix.
The empty-skeleton-grid part of the same report is already addressed
by the 300ms lazy render in #352 — Rekoo-PS just needs to update from
v3.32.1-beta.0 to v3.32.2-beta.0+.
Paul Nothaft
f81a8728e6