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.

docs/architecture.adoc

@@ -89,17 +89,33 @@ covering accented Latin place names (Slovak, Czech, Polish, German,
 ...). Labels in other scripts (Cyrillic, Greek, CJK, ...) won't render
 offline, since those glyph ranges aren't vendored.
 
-`public/js/map.js`'s `OFFLINE_THEME` also nudges a handful of color
-roles (background, water, wood, buildings, the two road-importance
-tiers) from `protomaps-themes-base`'s stock "light" theme towards the
-online "liberty" style's actual palette (sampled from its style JSON),
-so Online/Offline don't look like two different apps. This is
-deliberately partial — most roles (labels, casings, minor terrain
-fills, ...) are left at their theme defaults — not the kind of
-full per-layer recolor a previous iteration of this app did (and
-removed, along with any dependency on OsmAnd's own tile server, which
-this app cannot use per OsmAnd's terms restricting tile use to "personal,
-non-commercial use within OsmAnd applications and platforms").
+`public/js/map.js`'s `OFFLINE_THEME` nudges a couple dozen color roles
+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. A few of these values 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 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) — background, the park/protected-area green, the
+two road-importance tiers, and the park-boundary line color. The rest
+are reasoned to match that same warm family (olive greens, muted blue)
+rather than sourced. This is deliberately partial — labels, casings,
+and roles with no clean real-color anchor are left at theme
+defaults — not the kind of full per-layer recolor a previous iteration
+of this app did (and removed, along with any dependency on OsmAnd's
+own tile server, which this app cannot use per OsmAnd's terms
+restricting tile use to "personal, non-commercial use within OsmAnd
+applications and platforms").
++
+Recreating the *color choices* is fine — that's not the kind of thing
+a data license restricts — but the actual Park Tiles *service* stays
+off-limits: its OSM/terrain layers are licensed through Mapbox Atlas
+(a commercial, non-sublicensable data service scoped to NPS), and it's
+built for park visitors specifically (park-unit and trailhead
+labeling prioritized), not general-purpose worldwide cartography.
 
 No PMTiles file ships with the repository — it is expected to be
 supplied locally (see `docs/development.adoc`) and stays gitignored

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() {