Recolor the offline theme towards NPS Park Tiles' palette

Extended OFFLINE_THEME's color-role overrides to lean into the warm,
Harpers-Ferry-Center-derived look of the National Park Service's own "Park
Tiles" cartography, rather than the cooler default protomaps-themes-base
palette. A handful of values (background, the park/protected-area green, the
two road-importance tiers, the park-boundary line color) are the genuine
paint colors pulled from a public Park Tiles style JSON — the "Imagery"
variant is the only one of NPS's four styles served from a plain,
unauthenticated URL; "Standard"/"Slate"/"Light" resolve through Mapbox
Studio's private API with an access token, which isn't something to
piggyback on even though it's technically visible in their own JS bundle.
The rest of the palette (forest/scrub greens, water, sand, buildings) is
reasoned to match that same family rather than sourced.

Recreating the color choices is fine — that's not the kind of thing a data
license restricts. What stays off-limits is their actual tile service: its
OSM/terrain layers are licensed through Mapbox Atlas, a commercial,
non-sublicensable data service scoped to NPS's own use.

public/js/map.js

@@ -20,23 +20,46 @@ const ONLINE_STYLE = "https://tiles.openfreemap.org/styles/liberty";
 const protocol = new pmtiles.Protocol();
 addProtocol("pmtiles", protocol.tile);
 
-// A few color roles nudged from protomaps-themes-base's stock "light" theme
-// towards the online OpenFreeMap "liberty" style's actual palette (sampled
-// from its style JSON — see docs/architecture.adoc), so switching between
-// Online/Offline doesn't look like two different apps. Not a full recolor:
-// most roles (labels, casings, minor terrain fills, ...) are left at their
-// theme defaults.
+// Nudged from protomaps-themes-base's stock "light" theme towards the
+// National Park Service's own "Park Tiles" cartography — a warm,
+// Harpers-Ferry-Center-derived look. Not their actual map: a handful of
+// values below (marked) are the genuine paint colors pulled from a public
+// Park Tiles style JSON
+// (nps.gov/lib/npmap.js/style/ck72fwp2642dv07o7tbqinvz4.json, the "Imagery"
+// variant — the only one of their four styles served from a plain,
+// unauthenticated URL; "Standard"/"Slate"/"Light" resolve through Mapbox
+// Studio's private API with an access token, which isn't something to
+// piggyback on even though it's technically visible in their own JS bundle).
+// The rest are reasoned to match that same family (warm cream ground, olive
+// greens, muted blue) rather than sourced. Not a full recolor: labels,
+// casings, and roles with no clean real-color anchor are left at theme
+// defaults.
+//
+// Recreating the color choices is legitimate — that's not the kind of thing
+// a data license restricts (see docs/architecture.adoc's "Offline maps"
+// section) — what stays off-limits is their actual tile *service*: its
+// OSM/terrain layers are licensed through Mapbox Atlas, a commercial,
+// non-sublicensable data service scoped to NPS.
 const OFFLINE_THEME = {
   ...protomaps_themes_base.namedTheme("light"),
-  background: "#f8f4f0",
-  earth: "#f8f4f0",
-  water: "#9ebdff",
-  wood_a: "#ace38c",
-  wood_b: "#ace38c",
-  buildings: "#dcd9d6",
-  highway: "#f2934a",
-  major: "#ffeeaa",
-  link: "#ffeeaa",
+  background: "#f9f6ef", // real: Park Tiles' own background, hsl(40, 37%, 97%)
+  earth: "#f9f6ef",
+  water: "#a3cedf",
+  wood_a: "#c3d9a0",
+  wood_b: "#b3c98f",
+  scrub_a: "#d6e3b8",
+  scrub_b: "#cddba8",
+  park_a: "#c8e2a0",
+  park_b: "#b3e378", // real: Park Tiles' protected-area/park-point green
+  sand: "#f0e4c4",
+  beach: "#f0e4c4",
+  buildings: "#ded7cc",
+  pedestrian: "#e9e2d8",
+  highway: "#fdefbe", // real: Park Tiles' primary/highway road color
+  major: "#fef7dd", // real: Park Tiles' secondary road color
+  minor: "#fffdf8",
+  link: "#fef7dd",
+  boundaries: "#546619", // real: Park Tiles' park-boundary line color
 };
 
 function offlineStyle() {