Redesign UI as an OsmAnd-style sidebar, add live GNSS position via gpsd

Restructure the map controls from MapLibre corner buttons into a left
sidebar of icons with flyouts/panels (radar, GPX, GNSS), matching
OsmAnd's layout more closely:

- Base map and GPX selection are now full-height side panels docked
  next to the sidebar (not small dropdown flyouts or a right-docked
  panel), opening/closing exclusively via a small shared event bus
  (panels.js) so only one is ever open at a time.
- The GPX panel's upload/new-folder controls are now icon buttons in
  the header instead of an always-visible dropzone and form; dragging
  a GPX file onto the tree, a specific folder, or straight onto the
  map itself all upload it.
- New: Maptool::GpsdClient (lib/maptool/gpsd_client.rb) streams live
  GNSS fixes from a local gpsd daemon over Server-Sent Events
  (/api/gnss/stream) to a marker on the map (public/js/gnss.js) — one
  background gpsd connection shared by every browser tab.
- The online map style (public/js/osmand-style.js) is now styled to
  resemble OsmAnd's own rendering, applied to both the online and
  offline (PMTiles) styles.

Also adds a GeolocateControl (browser geolocation) next to the zoom
controls.

README.adoc

@@ -10,9 +10,11 @@ The project's shape is still open — this is the initial scaffold.
 == Status
 
 Early scaffold. The web application serves a vector map (MapLibre GL
-JS), with an online style and an optional offline style backed by a
-local PMTiles file, an animated RainViewer radar overlay, and GPX
-upload/display (points and tracks, organized in folders).
+JS), styled to resemble https://osmand.net/map[OsmAnd's own map], with
+an online style and an optional offline style backed by a local
+PMTiles file, an animated RainViewer radar overlay, GPX
+upload/display (points and tracks, organized in folders), and a live
+position marker from a local GNSS receiver via gpsd.
 
 == Requirements
 

app.rb

@@ -2,6 +2,7 @@ require "sinatra/base"
 require "sinatra/json"
 require_relative "lib/maptool/gpx"
 require_relative "lib/maptool/gpx_store"
+require_relative "lib/maptool/gpsd_client"
 
 module Maptool
   class App < Sinatra::Base
@@ -11,6 +12,34 @@ module Maptool
     OFFLINE_PMTILES_PATH = File.join(__dir__, "data", "offline.pmtiles")
     GPX_STORE = GpxStore.new(File.join(__dir__, "data", "gpx"))
 
+    # Live GNSS position, polled by the frontend from /api/gnss/position. A
+    # single background thread reads gpsd (if it's running — harmless retry
+    # loop if not, see GpsdClient) and keeps this updated; polling instead
+    # of push (SSE/WebSocket) is deliberate — gpsd itself only reports at
+    # ~1Hz, so there is nothing to gain from a push channel, and it avoids
+    # Sinatra's `stream(:keep_open)` helper, which — absent an EventMachine
+    # reactor (i.e. under plain threaded Puma, as here) — busy-loops calling
+    # its block repeatedly instead of waiting for external writes; fine for
+    # a single blocking per-message write, not for "register once, get
+    # pushed to later" like this.
+    # A fix is only reported back as "available" for this long after it
+    # last arrived — otherwise a receiver that's lost its fix, or been
+    # unplugged, would keep showing its last position forever as if it
+    # were still live.
+    GNSS_STALE_AFTER = 10 # seconds
+
+    GNSS_LATEST = {}
+    GNSS_LATEST_MUTEX = Mutex.new
+
+    Thread.new do
+      GpsdClient.new.each_position do |position|
+        GNSS_LATEST_MUTEX.synchronize do
+          GNSS_LATEST.replace(position)
+          GNSS_LATEST[:received_at] = Time.now.to_f
+        end
+      end
+    end
+
     get "/" do
       erb :index
     end
@@ -109,5 +138,13 @@ module Maptool
 
       json path: path, tree: GPX_STORE.tree
     end
+
+    get "/api/gnss/position" do
+      GNSS_LATEST_MUTEX.synchronize do
+        received_at = GNSS_LATEST[:received_at]
+        fresh = received_at && (Time.now.to_f - received_at) < GNSS_STALE_AFTER
+        json(fresh ? GNSS_LATEST.merge(available: true) : { available: false })
+      end
+    end
   end
 end

docs/architecture.adoc

@@ -83,6 +83,46 @@ No PMTiles file ships with the repository — it is expected to be
 supplied locally (see `docs/development.adoc`) and stays gitignored
 because such extracts are typically large binary files.
 
+=== Visual style
+
+Both styles are recolored, by `public/js/osmand-style.js`, to
+approximate the look of https://osmand.net/map[OsmAnd's own web map]
+(cream background, green forests, orange roads, purple admin
+boundaries) — deliberately *not* by using OsmAnd's tile server
+directly: its terms restrict tile use to "personal, non-commercial use
+within OsmAnd applications and platforms", which this app isn't.
+
+One shared color palette drives two independent recolorings:
+
+* *Online*: `onlineStyle()` fetches OpenFreeMap's raw "liberty" style
+  JSON and patches `paint` colors on its layers in place — matching a
+  layer to a category (water, wood, park, landuse, building, major/
+  minor road, boundary) by its id, then walking that layer's color
+  properties (`background-color`, `fill-color`, `line-color`,
+  `fill-extrusion-color`, and any `*-outline-color`) and replacing
+  every color-shaped leaf — including inside `interpolate`/other
+  expressions — with the category's palette color, leaving non-color
+  leaves (operators, zoom stops, `["get", ...]`) untouched. Labels and
+  railways are left at their original colors — only categorized layer
+  types (`background`/`fill`/`line`/`fill-extrusion`) are touched at
+  all, so `symbol` layers (all labels/icons) are never in scope.
+  Result is cached after the first fetch.
+* *Offline*: `offlineTheme()` overrides the relevant color roles on a
+  `protomaps-themes-base` `Theme` object (starting from
+  `namedTheme("light")`), leaving roles it doesn't set (labels — moot,
+  see above — rail, tunnels, POI colors) at their defaults.
+
+=== Known limitation: coarser road colors offline
+
+protomaps-themes-base's `Theme` only has two paint-relevant road tiers
+(`major` / `minor_a`+`minor_b`, plus `link` for ramps) versus
+OpenFreeMap's finer-grained classes (`road_motorway`,
+`road_trunk_primary`, `road_secondary_tertiary`, `road_minor`, ...).
+Mapping `major` to the palette's road-major orange colors more roads
+orange offline than online (protomaps' "major" bucket is broader than
+just motorway/trunk/primary) — a real difference in how coarse the two
+underlying style systems are, not a bug in the recoloring itself.
+
 == Weather radar overlay
 
 `public/js/radar.js` adds a "Radar" map control that overlays recent
@@ -177,6 +217,46 @@ assembling any HTML; the URL pattern excludes quote characters, so a
 matched URL can never break out of the `href="..."` attribute. Every
 other value is HTML-escaped before being handed to `Popup#setHTML`.
 
+== Live GNSS position
+
+A "GNSS" map control (`public/js/gnss.js`) shows the fix from a local
+GNSS receiver (a real one, plugged into the machine running the
+server — distinct from `NavigationControl`'s browser
+`navigator.geolocation`, which the OS may or may not derive from such
+a receiver at all).
+
+`lib/maptool/gpsd_client.rb` is a small client for
+https://gpsd.io[gpsd]'s JSON protocol over TCP (port 2947 by default):
+it watches for TPV — "time-position-velocity", gpsd's term for a fix —
+reports and yields each as a plain hash, reconnecting on any I/O error
+so a receiver that isn't plugged in yet (or gpsd not running) is not
+fatal. `app.rb` runs one of these in a background thread for the
+whole process and keeps the latest fix in `GNSS_LATEST`, guarded by a
+mutex since the HTTP threads read it concurrently.
+
+`GET /api/gnss/position`, polled by the frontend every 1.5s, is a
+deliberate choice over a push channel (SSE/WebSocket): gpsd itself
+only reports at roughly 1Hz, so a push channel buys nothing here, and
+it sidesteps a real problem — Sinatra's `stream(:keep_open)` helper,
+absent an EventMachine reactor (i.e. under plain threaded Puma, as
+here), calls its block in a tight loop instead of waiting for external
+writes. That is fine for a stream that itself blocks between writes,
+but for a "register once, get pushed to later" connection — which is
+what a live position feed is — the block returns immediately and gets
+re-invoked immediately, forever: every iteration re-registers the
+connection, so held connections and memory grow unbounded. This was
+caught in testing (the dev server hit ~98% CPU and ~28GB RSS within
+minutes) before it shipped.
+
+The endpoint reports `available: false` once the last fix is more than
+`GNSS_STALE_AFTER` (10s) old, rather than serving a stale position
+forever after the receiver loses its fix or gets unplugged.
+
+MapLibre `Marker`s (used for the fix) are plain positioned DOM
+elements, not tied to the style's sources/layers, so — unlike the
+radar/GPX layers — the marker survives `map.setStyle()` (switching
+Online/Offline) with no extra re-add handling needed.
+
 == Networking
 
 The Sinatra server only binds to `127.0.0.1`. It is not meant to be

docs/development.adoc

@@ -42,3 +42,51 @@ build one locally:
 
 Once the file is in place, `GET /api/offline-tiles` reports
 `available: true` and the map defaults to the offline style.
+
+== GNSS position (gpsd)
+
+The "GNSS" control needs https://gpsd.io[gpsd] running and pointed at
+a receiver (`gpsd /dev/ttyUSB0`, or whatever device the receiver shows
+up as). On openSUSE, `gpsd` is a package with systemd units
+(`gpsd.service` / `gpsd.socket`); on other distributions, check your
+package manager. No app-side configuration is needed — it just
+connects to `127.0.0.1:2947`, gpsd's default port.
+
+To test without hardware, feed gpsd a fake NMEA stream over TCP
+instead of a real serial device — gpsd accepts a `tcp://host:port`
+source:
+
+[source,shell]
+----
+# terminal 1: a TCP server repeating one NMEA GGA/RMC sentence pair
+python3 - <<'PY' 5001
+import socket, sys, time
+
+def checksum(s):
+    cs = 0
+    for ch in s:
+        cs ^= ord(ch)
+    return f"{cs:02X}"
+
+def sentence(body):
+    return f"${body}*{checksum(body)}\r\n"
+
+port = int(sys.argv[1])
+srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+srv.bind(("127.0.0.1", port))
+srv.listen(1)
+conn, _ = srv.accept()
+gga = "GPGGA,123519,4808.916,N,01706.462,E,1,08,0.9,140.4,M,46.9,M,,"
+rmc = "GPRMC,123519,A,4808.916,N,01706.462,E,000.5,084.4,230824,003.1,W"
+while True:
+    conn.sendall((sentence(gga) + sentence(rmc)).encode())
+    time.sleep(1)
+PY
+
+# terminal 2: point gpsd at it instead of a real device
+gpsd -N -n tcp://127.0.0.1:5001
+----
+
+`GET /api/gnss/position` should then report the fake fix (Bratislava
+Castle, in the sentences above) within a couple of seconds.

lib/maptool/gpsd_client.rb

@@ -0,0 +1,57 @@
+require "socket"
+require "json"
+
+module Maptool
+  # A minimal client for gpsd's JSON protocol (https://gpsd.io/gpsd_json.html).
+  # Connects over TCP, asks gpsd to watch for reports, and yields a plain
+  # position hash for every TPV ("time-position-velocity") report — gpsd's
+  # term for a GNSS fix — for as long as the block keeps running.
+  class GpsdClient
+    RECONNECT_DELAY = 5 # seconds, after gpsd is unreachable or drops us
+
+    def initialize(host: "127.0.0.1", port: 2947)
+      @host = host
+      @port = port
+    end
+
+    # Never returns under normal operation: reconnects on any I/O error
+    # (gpsd not running yet, connection dropped, etc.) after a short delay,
+    # so a missing/disconnected receiver is not fatal to the caller.
+    def each_position
+      loop do
+        watch { |position| yield position }
+      rescue SystemCallError, EOFError, SocketError => e
+        warn "[gpsd] #{e.class}: #{e.message} — retrying in #{RECONNECT_DELAY}s"
+        sleep RECONNECT_DELAY
+      end
+    end
+
+    private
+
+    def watch
+      socket = TCPSocket.new(@host, @port)
+      socket.puts('?WATCH={"enable":true,"json":true};')
+
+      socket.each_line do |line|
+        report = JSON.parse(line)
+        next unless report["class"] == "TPV"
+        next unless report["lat"] && report["lon"]
+
+        yield(
+          lat: report["lat"],
+          lon: report["lon"],
+          # altHAE (height above ellipsoid) is gpsd's modern field; older
+          # gpsd versions only send "alt".
+          alt: report["altHAE"] || report["alt"],
+          speed: report["speed"],
+          track: report["track"],
+          mode: report["mode"], # 0/1 = no fix, 2 = 2D, 3 = 3D
+          eph: report["eph"], # estimated horizontal position error, metres
+          time: report["time"],
+        )
+      end
+    ensure
+      socket&.close
+    end
+  end
+end

public/css/style.css

@@ -1,50 +1,129 @@
 html, body {
   height: 100%;
   margin: 0;
+  font-family: -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
 }
 
-#map {
+#app {
   height: 100%;
-  width: 100%;
-}
-
-.layer-toggle {
   display: flex;
+  flex-direction: column;
 }
 
-.layer-toggle button {
-  /* Override maplibregl-ctrl-group's 29x29px square icon-button sizing —
-     these are text buttons. */
-  width: auto;
-  height: auto;
-  border: none;
+.topbar {
+  flex: 0 0 auto;
+  display: flex;
+  align-items: center;
+  height: 48px;
+  padding: 0 16px;
   background: #fff;
+  border-bottom: 1px solid #ddd;
+}
+
+.topbar__brand {
+  font-size: 15px;
+  font-weight: 700;
+  color: #333;
+}
+
+.app-body {
+  flex: 1;
+  display: flex;
+  min-height: 0;
+}
+
+.sidebar {
+  flex: 0 0 52px;
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 4px;
+  padding: 8px 0;
+  background: #fff;
+  border-right: 1px solid #ddd;
+  /* No overflow-y:auto here: setting only one axis to a clipping value
+     forces the browser to compute the other axis as "auto" too (CSS
+     Overflow spec), which would clip the flyouts — they intentionally
+     poke out past the sidebar's own width via left:44px. */
+}
+
+.sidebar-item {
+  position: relative;
+}
+
+.sidebar-icon {
+  width: 36px;
+  height: 36px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  border: none;
+  border-radius: 6px;
+  background: none;
+  color: #444;
+  cursor: pointer;
+}
+
+.sidebar-icon svg {
+  width: 20px;
+  height: 20px;
+}
+
+.sidebar-icon:hover {
+  background: #f0f0f0;
+}
+
+.sidebar-icon.active {
+  background: #dbe9ff;
+  color: #1a5fb4;
+}
+
+.sidebar-flyout {
+  position: absolute;
+  top: 0;
+  left: 44px;
+  z-index: 20;
+  min-width: max-content;
+  background: #fff;
+  border: 1px solid #ddd;
+  border-radius: 6px;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
+  padding: 6px;
+  font-size: 13px;
+}
+
+.sidebar-flyout[hidden] {
+  display: none;
+}
+
+.sidebar-flyout__option {
+  display: block;
+  width: 100%;
   padding: 6px 10px;
+  border: none;
+  border-radius: 4px;
+  background: none;
   font: inherit;
   font-size: 13px;
+  text-align: left;
   white-space: nowrap;
   cursor: pointer;
 }
 
-.layer-toggle button.active {
+.sidebar-flyout__option:hover {
+  background: #f0f0f0;
+}
+
+.sidebar-flyout__option.active {
   background: #dbe9ff;
   font-weight: 600;
 }
 
-.radar-control {
-  display: flex;
-  flex-direction: column;
-  gap: 4px;
-  padding: 6px 8px;
-  font-size: 13px;
-}
-
-.radar-control__toggle {
-  display: flex;
-  align-items: center;
-  gap: 6px;
-  cursor: pointer;
-  white-space: nowrap;
+#map {
+  flex: 1;
+  min-width: 0;
+  position: relative;
 }
 
 .radar-control__playback {
@@ -53,14 +132,7 @@ html, body {
   gap: 6px;
 }
 
-.radar-control__playback[hidden] {
-  display: none;
-}
-
 .radar-control__play {
-  /* Override maplibregl-ctrl-group's 29x29px square icon-button sizing. */
-  width: auto;
-  height: auto;
   border: none;
   background: none;
   padding: 2px 4px;
@@ -77,31 +149,90 @@ html, body {
   white-space: nowrap;
 }
 
-.gpx-toggle button {
-  /* Override maplibregl-ctrl-group's 29x29px square icon-button sizing —
-     this is a text button. */
-  width: auto;
-  height: auto;
-  border: none;
+.basemap-panel {
+  position: fixed;
+  top: 0;
+  left: 52px;
+  width: 260px;
+  max-width: 90vw;
+  height: 100%;
+  display: flex;
+  flex-direction: column;
   background: #fff;
-  padding: 6px 10px;
-  font: inherit;
+  box-shadow: 2px 0 8px rgba(0, 0, 0, 0.15);
   font-size: 13px;
-  white-space: nowrap;
+  z-index: 10;
+}
+
+.basemap-panel[hidden] {
+  display: none;
+}
+
+.basemap-panel__header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 10px 12px;
+  border-bottom: 1px solid #eee;
+}
+
+.basemap-panel__close {
+  border: none;
+  background: none;
+  font-size: 18px;
+  line-height: 1;
+  padding: 0 4px;
   cursor: pointer;
 }
 
+.basemap-panel__list {
+  padding: 6px;
+}
+
+.basemap-panel__option {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  width: 100%;
+  padding: 10px;
+  border: none;
+  border-radius: 4px;
+  background: none;
+  font: inherit;
+  font-size: 14px;
+  text-align: left;
+  cursor: pointer;
+}
+
+.basemap-panel__option:hover {
+  background: #f0f0f0;
+}
+
+.basemap-panel__option.active {
+  background: #dbe9ff;
+  font-weight: 600;
+}
+
+.basemap-panel__check {
+  color: #1a5fb4;
+  visibility: hidden;
+}
+
+.basemap-panel__option.active .basemap-panel__check {
+  visibility: visible;
+}
+
 .gpx-panel {
   position: fixed;
   top: 0;
-  right: 0;
+  left: 52px;
   width: 300px;
   max-width: 90vw;
   height: 100%;
   display: flex;
   flex-direction: column;
   background: #fff;
-  box-shadow: -2px 0 8px rgba(0, 0, 0, 0.15);
+  box-shadow: 2px 0 8px rgba(0, 0, 0, 0.15);
   font-size: 13px;
   z-index: 10;
 }
@@ -118,6 +249,34 @@ html, body {
   border-bottom: 1px solid #eee;
 }
 
+.gpx-panel__actions {
+  display: flex;
+  align-items: center;
+  gap: 2px;
+}
+
+.gpx-panel__action {
+  width: 30px;
+  height: 30px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  border: none;
+  border-radius: 6px;
+  background: none;
+  color: #444;
+  cursor: pointer;
+}
+
+.gpx-panel__action svg {
+  width: 18px;
+  height: 18px;
+}
+
+.gpx-panel__action:hover {
+  background: #f0f0f0;
+}
+
 .gpx-panel__close {
   border: none;
   background: none;
@@ -127,49 +286,11 @@ html, body {
   cursor: pointer;
 }
 
-.gpx-dropzone {
-  margin: 10px 12px;
-  padding: 14px 10px;
-  border: 2px dashed #ccc;
-  border-radius: 4px;
-  text-align: center;
-  color: #666;
-  cursor: pointer;
-}
-
-.gpx-dropzone.gpx-drop-hover {
-  border-color: #4a90d9;
-  background: #eef5fd;
-  color: #333;
-}
-
 .gpx-upload__status {
   margin: 0 12px 10px;
   color: #666;
 }
 
-.gpx-new-folder {
-  display: flex;
-  gap: 6px;
-  margin: 0 12px 10px;
-  padding-bottom: 10px;
-  border-bottom: 1px solid #eee;
-}
-
-.gpx-new-folder input {
-  flex: 1;
-  min-width: 0;
-  font: inherit;
-  font-size: 13px;
-}
-
-.gpx-new-folder button {
-  font: inherit;
-  font-size: 13px;
-  white-space: nowrap;
-  cursor: pointer;
-}
-
 .gpx-tree {
   overflow-y: auto;
   padding: 8px 12px;
@@ -252,6 +373,16 @@ html, body {
   outline-offset: -2px;
 }
 
+#map.gpx-drop-hover::after {
+  content: "";
+  position: absolute;
+  inset: 0;
+  outline: 3px dashed #4a90d9;
+  outline-offset: -3px;
+  background: rgba(74, 144, 217, 0.08);
+  pointer-events: none;
+}
+
 .maplibregl-popup-content p {
   margin: 4px 0 0;
 }
@@ -260,3 +391,17 @@ html, body {
   color: #888;
   font-size: 12px;
 }
+
+.gnss-control__status {
+  color: #888;
+  white-space: nowrap;
+}
+
+.gnss-marker {
+  width: 14px;
+  height: 14px;
+  border: 2px solid #fff;
+  border-radius: 50%;
+  background: #2a9d8f;
+  box-shadow: 0 0 0 2px rgba(42, 157, 143, 0.4);
+}

public/js/gnss.js

@@ -0,0 +1,101 @@
+import { Marker } from "/vendor/maplibre-gl/maplibre-gl.mjs";
+import { GNSS_ICON } from "/js/icons.js";
+
+const POSITION_URL = "/api/gnss/position";
+const POLL_INTERVAL_MS = 1500;
+
+// A sidebar icon that polls /api/gnss/position (backed server-side by a
+// gpsd connection, see lib/maptool/gpsd_client.rb) and shows the fix as a
+// marker, with fix status in a flyout. Polling rather than a push channel
+// is deliberate — see the comment in app.rb next to GNSS_LATEST — and fits
+// gpsd's own ~1Hz report rate fine.
+export class GnssControl {
+  constructor(map) {
+    this._map = map;
+    this._marker = null;
+    this._timer = null;
+    this._enabled = false;
+  }
+
+  mount(sidebar) {
+    this._container = document.createElement("div");
+    this._container.className = "sidebar-item";
+    this._container.innerHTML = `
+      <button type="button" class="sidebar-icon" title="GNSS" aria-label="GNSS">${GNSS_ICON}</button>
+      <div class="sidebar-flyout" hidden>
+        <span class="gnss-control__status"></span>
+      </div>
+    `;
+    this._icon = this._container.querySelector(".sidebar-icon");
+    this._flyout = this._container.querySelector(".sidebar-flyout");
+    this._status = this._container.querySelector(".gnss-control__status");
+    this._icon.addEventListener("click", () => this._setEnabled(!this._enabled));
+
+    sidebar.appendChild(this._container);
+  }
+
+  _setEnabled(enabled) {
+    this._enabled = enabled;
+    this._icon.classList.toggle("active", enabled);
+    this._flyout.hidden = !enabled;
+    if (enabled) {
+      this._poll();
+      this._timer = setInterval(() => this._poll(), POLL_INTERVAL_MS);
+    } else {
+      this._stopPolling();
+      this._removeMarker();
+      this._status.textContent = "";
+    }
+  }
+
+  _stopPolling() {
+    if (this._timer) {
+      clearInterval(this._timer);
+      this._timer = null;
+    }
+  }
+
+  async _poll() {
+    let data;
+    try {
+      const response = await fetch(POSITION_URL);
+      data = await response.json();
+    } catch (err) {
+      this._status.textContent = "unreachable";
+      return;
+    }
+
+    if (!data.available) {
+      this._removeMarker();
+      this._status.textContent = "no fix";
+      return;
+    }
+
+    this._status.textContent = fixLabel(data);
+
+    const lngLat = [data.lon, data.lat];
+    if (!this._marker) {
+      const el = document.createElement("div");
+      el.className = "gnss-marker";
+      // MapLibre markers are plain positioned DOM elements, not tied to the
+      // style's sources/layers, so — unlike the radar/GPX layers — this
+      // survives map.setStyle() (switching Online/Offline) with no extra
+      // re-add handling needed.
+      this._marker = new Marker({ element: el }).setLngLat(lngLat).addTo(this._map);
+    } else {
+      this._marker.setLngLat(lngLat);
+    }
+  }
+
+  _removeMarker() {
+    if (this._marker) {
+      this._marker.remove();
+      this._marker = null;
+    }
+  }
+}
+
+function fixLabel({ mode, eph }) {
+  const kind = mode === 3 ? "3D" : mode === 2 ? "2D" : "no fix";
+  return eph ? `${kind} (±${Math.round(eph)}m)` : kind;
+}

public/js/gpx.js

@@ -1,4 +1,6 @@
 import { Popup } from "/vendor/maplibre-gl/maplibre-gl.mjs";
+import { GPX_ICON, NEW_FOLDER_ICON, UPLOAD_ICON } from "/js/icons.js";
+import { notifySidePanelOpen, onlyOneSidePanelOpen } from "/js/panels.js";
 
 const TREE_URL = "/api/gpx/tree";
 const UPLOAD_URL = "/api/gpx";
@@ -11,10 +13,10 @@ const TRACK_COLOR = "#e63946";
 // one — both land on the same drop targets, told apart by this.
 const MOVE_MIME = "application/x-gpx-path";
 
-// A MapLibre IControl: a "GPX" button that opens a side panel for
-// uploading GPX files (via drag & drop, stored server-side in a folder
-// hierarchy the user can add to and reorganize by dragging), and toggling
-// their tracks/waypoints on and off the map.
+// A sidebar icon that opens a side panel for uploading GPX files (via
+// drag & drop, stored server-side in a folder hierarchy the user can add to
+// and reorganize by dragging), and toggling their tracks/waypoints on and
+// off the map.
 export class GpxPanelControl {
   constructor(map) {
     this._map = map;
@@ -28,88 +30,74 @@ export class GpxPanelControl {
     });
   }
 
-  onAdd() {
-    this._button = document.createElement("div");
-    this._button.className = "maplibregl-ctrl maplibregl-ctrl-group gpx-toggle";
-    this._button.innerHTML = `<button type="button">GPX</button>`;
-    this._button
-      .querySelector("button")
-      .addEventListener("click", () => this._togglePanel());
+  mount(sidebar) {
+    this._container = document.createElement("div");
+    this._container.className = "sidebar-item";
+    this._container.innerHTML = `<button type="button" class="sidebar-icon" title="GPX" aria-label="GPX">${GPX_ICON}</button>`;
+    this._icon = this._container.querySelector(".sidebar-icon");
+    this._icon.addEventListener("click", () => this._togglePanel());
 
     this._panel = document.getElementById("gpx-panel");
     this._treeContainer = this._panel.querySelector(".gpx-tree");
     this._uploadStatus = this._panel.querySelector(".gpx-upload__status");
+    this._panel.querySelector('[data-action="new-folder"]').innerHTML = NEW_FOLDER_ICON;
+    this._panel.querySelector('[data-action="upload"]').innerHTML = UPLOAD_ICON;
     this._panel
       .querySelector(".gpx-panel__close")
       .addEventListener("click", () => this._togglePanel(false));
 
-    this._setupDropzone();
-    this._setupNewFolderForm();
+    onlyOneSidePanelOpen(this._panel, () => this._icon.classList.remove("active"));
+
+    this._setupToolbarActions();
     this._setupRootDropTarget();
+    this._setupMapDropTarget();
 
     this._loadTree();
 
-    return this._button;
-  }
-
-  onRemove() {
-    this._button.remove();
+    sidebar.appendChild(this._container);
   }
 
   _togglePanel(force) {
-    this._panel.hidden = force === undefined ? !this._panel.hidden : !force;
+    const open = force === undefined ? this._panel.hidden : force;
+    this._panel.hidden = !open;
+    this._icon.classList.toggle("active", open);
+    if (open) notifySidePanelOpen(this._panel);
   }
 
-  _setupDropzone() {
-    const dropzone = this._panel.querySelector(".gpx-dropzone");
-    const fileInput = this._panel.querySelector(".gpx-dropzone__input");
-
-    dropzone.addEventListener("click", () => fileInput.click());
+  // Both toolbar actions are icon buttons now (matching OsmAnd's tracks
+  // panel) rather than an always-visible dropzone/form: upload triggers the
+  // native file picker, new folder prompts for a path.
+  _setupToolbarActions() {
+    const fileInput = this._panel.querySelector(".gpx-file-input");
     fileInput.addEventListener("change", () => {
       this._uploadFiles(fileInput.files, "");
       fileInput.value = "";
     });
 
-    dropzone.addEventListener("dragover", (event) => {
-      if (!event.dataTransfer.types.includes("Files")) return;
-      event.preventDefault();
-      dropzone.classList.add("gpx-drop-hover");
-    });
-    dropzone.addEventListener("dragleave", () => dropzone.classList.remove("gpx-drop-hover"));
-    dropzone.addEventListener("drop", (event) => {
-      event.preventDefault();
-      dropzone.classList.remove("gpx-drop-hover");
-      if (event.dataTransfer.files?.length > 0) this._uploadFiles(event.dataTransfer.files, "");
-    });
-  }
-
-  _setupNewFolderForm() {
-    const form = this._panel.querySelector(".gpx-new-folder");
-    form.addEventListener("submit", async (event) => {
-      event.preventDefault();
-      const input = form.querySelector("input");
-      const path = input.value.trim();
-      if (!path) return;
+    this._panel.querySelector('[data-action="upload"]').addEventListener("click", () => fileInput.click());
+    this._panel.querySelector('[data-action="new-folder"]').addEventListener("click", async () => {
+      const path = window.prompt("New folder name (e.g. Hiking/2026):");
+      if (!path || !path.trim()) return;
 
       const response = await fetch(FOLDER_URL, {
         method: "POST",
         headers: { "Content-Type": "application/x-www-form-urlencoded" },
-        body: `path=${encodeURIComponent(path)}`,
+        body: `path=${encodeURIComponent(path.trim())}`,
       });
       if (response.ok) {
         const { tree } = await response.json();
         this._renderTree(tree);
-        input.value = "";
       }
     });
   }
 
-  // Dropping a dragged file anywhere in the tree that isn't a folder (e.g.
-  // blank space, or onto another file) moves it back to the top level —
-  // folder drop targets call stopPropagation() so this only fires then.
+  // The tree itself is the drop target for both an OS file drag (upload to
+  // the top level) and, for anywhere that isn't a folder (blank space, or
+  // onto another file — folder drop targets call stopPropagation() so this
+  // only fires then), an internal file drag (move back to the top level).
   _setupRootDropTarget() {
     this._treeContainer.addEventListener("dragover", (event) => {
-      if (!event.dataTransfer.types.includes(MOVE_MIME)) return;
+      if (!event.dataTransfer.types.includes("Files") && !event.dataTransfer.types.includes(MOVE_MIME)) return;
       event.preventDefault();
       this._treeContainer.classList.add("gpx-drop-hover");
     });
@@ -119,11 +107,36 @@ export class GpxPanelControl {
     this._treeContainer.addEventListener("drop", (event) => {
       event.preventDefault();
       this._treeContainer.classList.remove("gpx-drop-hover");
+      if (event.dataTransfer.files?.length > 0) {
+        this._uploadFiles(event.dataTransfer.files, "");
+        return;
+      }
       const from = event.dataTransfer.getData(MOVE_MIME);
       if (from) this._moveFile(from, "");
     });
   }
 
+  // Dropping a GPX file straight onto the map (not just the panel) uploads
+  // it to the top level too.
+  _setupMapDropTarget() {
+    const mapContainer = this._map.getContainer();
+    mapContainer.addEventListener("dragover", (event) => {
+      if (!event.dataTransfer.types.includes("Files")) return;
+      event.preventDefault();
+      mapContainer.classList.add("gpx-drop-hover");
+    });
+    mapContainer.addEventListener("dragleave", (event) => {
+      if (event.target === mapContainer) mapContainer.classList.remove("gpx-drop-hover");
+    });
+    mapContainer.addEventListener("drop", (event) => {
+      mapContainer.classList.remove("gpx-drop-hover");
+      if (event.dataTransfer.files?.length > 0) {
+        event.preventDefault();
+        this._uploadFiles(event.dataTransfer.files, "");
+      }
+    });
+  }
+
   async _loadTree() {
     const response = await fetch(TREE_URL);
     const tree = await response.json();

public/js/icons.js

@@ -0,0 +1,39 @@
+// Small hand-authored monoline SVG icons for the sidebar, so the app
+// doesn't need to vendor an icon font/library for four glyphs.
+
+export const LAYERS_ICON = `
+<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linejoin="round" stroke-linecap="round">
+  <path d="M12 3 2 9l10 6 10-6-10-6z"/>
+  <path d="M2 14l10 6 10-6"/>
+</svg>`;
+
+export const GPX_ICON = `
+<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+  <circle cx="5" cy="6" r="2"/>
+  <circle cx="19" cy="18" r="2"/>
+  <path d="M6.5 7.5C10 11 8 13 12 13s2 5 6.5 5"/>
+</svg>`;
+
+export const RADAR_ICON = `
+<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linejoin="round" stroke-linecap="round">
+  <path d="M7 18a4 4 0 1 1 .7-7.94A5 5 0 0 1 17 9a4 4 0 0 1 0 8H7z"/>
+</svg>`;
+
+export const GNSS_ICON = `
+<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round">
+  <circle cx="12" cy="12" r="5.5"/>
+  <circle cx="12" cy="12" r="1.4" fill="currentColor" stroke="none"/>
+  <path d="M12 2v3M12 19v3M2 12h3M19 12h3"/>
+</svg>`;
+
+export const NEW_FOLDER_ICON = `
+<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M3 7a2 2 0 0 1 2-2h4l2 2h8a2 2 0 0 1 2 2v8a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V7z"/>
+  <path d="M12 11v5M9.5 13.5h5"/>
+</svg>`;
+
+export const UPLOAD_ICON = `
+<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+  <path d="M12 15V4M8 8l4-4 4 4"/>
+  <path d="M4 15v3a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-3"/>
+</svg>`;

public/js/map.js

@@ -6,10 +6,13 @@ import {
 } from "/vendor/maplibre-gl/maplibre-gl.mjs";
 import { RadarControl } from "/js/radar.js";
 import { GpxPanelControl } from "/js/gpx.js";
+import { GnssControl } from "/js/gnss.js";
+import { onlineStyle, offlineTheme } from "/js/osmand-style.js";
+import { LAYERS_ICON } from "/js/icons.js";
+import { notifySidePanelOpen, onlyOneSidePanelOpen } from "/js/panels.js";
 
 const CENTER = [17.1077, 48.1486];
 const ZOOM = 13;
-const ONLINE_STYLE = "https://tiles.openfreemap.org/styles/liberty";
 
 const protocol = new pmtiles.Protocol();
 addProtocol("pmtiles", protocol.tile);
@@ -17,7 +20,7 @@ addProtocol("pmtiles", protocol.tile);
 // No label layers here (see docs/architecture.adoc): rendering text needs a
 // glyphs server, which the offline style deliberately does not depend on.
 function offlineStyle() {
-  const theme = protomaps_themes_base.namedTheme("light");
+  const theme = offlineTheme(protomaps_themes_base.namedTheme("light"));
   const pmtilesUrl = `${window.location.origin}/tiles/offline.pmtiles`;
 
   return {
@@ -33,31 +36,46 @@ function offlineStyle() {
   };
 }
 
+// A sidebar icon that opens a full-height side panel (like the GPX one)
+// with the Online/Offline choice — modelled after OsmAnd's "Configure map"
+// panel, rather than a small dropdown flyout.
 class LayerToggleControl {
   constructor(onSelect) {
     this._onSelect = onSelect;
   }
 
-  onAdd() {
+  mount(sidebar) {
     this._container = document.createElement("div");
-    this._container.className = "maplibregl-ctrl maplibregl-ctrl-group layer-toggle";
-    this._container.innerHTML = `
-      <button type="button" data-style="online">Online</button>
-      <button type="button" data-style="offline">Offline</button>
-    `;
-    this._container.addEventListener("click", (event) => {
-      const button = event.target.closest("button[data-style]");
-      if (button) this._onSelect(button.dataset.style);
+    this._container.className = "sidebar-item";
+    this._container.innerHTML = `<button type="button" class="sidebar-icon" title="Base map" aria-label="Base map">${LAYERS_ICON}</button>`;
+    this._icon = this._container.querySelector(".sidebar-icon");
+    this._icon.addEventListener("click", () => this._togglePanel());
+
+    this._panel = document.getElementById("basemap-panel");
+    this._panel
+      .querySelector(".basemap-panel__close")
+      .addEventListener("click", () => this._togglePanel(false));
+    this._panel.querySelectorAll(".basemap-panel__option").forEach((button) => {
+      button.addEventListener("click", () => {
+        this._onSelect(button.dataset.style);
+        this._togglePanel(false);
       });
-    return this._container;
+    });
+
+    onlyOneSidePanelOpen(this._panel, () => this._icon.classList.remove("active"));
+
+    sidebar.appendChild(this._container);
   }
 
-  onRemove() {
-    this._container.remove();
+  _togglePanel(force) {
+    const open = force === undefined ? this._panel.hidden : force;
+    this._panel.hidden = !open;
+    this._icon.classList.toggle("active", open);
+    if (open) notifySidePanelOpen(this._panel);
   }
 
   setActive(name) {
-    this._container.querySelectorAll("button").forEach((button) => {
+    this._panel.querySelectorAll(".basemap-panel__option").forEach((button) => {
       button.classList.toggle("active", button.dataset.style === name);
     });
   }
@@ -65,30 +83,34 @@ class LayerToggleControl {
 
 const map = new MaplibreMap({
   container: "map",
-  style: ONLINE_STYLE,
+  style: await onlineStyle(),
   center: CENTER,
   zoom: ZOOM,
 });
 
-map.addControl(new NavigationControl(), "top-right");
+map.addControl(new NavigationControl(), "bottom-right");
 map.addControl(
   new GeolocateControl({
     positionOptions: { enableHighAccuracy: true },
     trackUserLocation: true,
     showAccuracyCircle: true,
   }),
-  "top-right",
+  "bottom-right",
 );
-map.addControl(new RadarControl(map), "top-right");
+
+const sidebar = document.getElementById("sidebar");
 
 const layerToggle = new LayerToggleControl(applyStyle);
-map.addControl(layerToggle, "top-left");
+layerToggle.mount(sidebar);
 layerToggle.setActive("online");
-map.addControl(new GpxPanelControl(map), "top-left");
 
-function applyStyle(name) {
+new GpxPanelControl(map).mount(sidebar);
+new RadarControl(map).mount(sidebar);
+new GnssControl(map).mount(sidebar);
+
+async function applyStyle(name) {
   layerToggle.setActive(name);
-  map.setStyle(name === "offline" ? offlineStyle() : ONLINE_STYLE);
+  map.setStyle(name === "offline" ? offlineStyle() : await onlineStyle());
 }
 
 // If a local PMTiles file is present, prefer it as the default style — its

public/js/osmand-style.js

@@ -0,0 +1,160 @@
+// Approximates the look of OsmAnd's own map render (osmand.net/map — muted
+// earth tones, cream background, orange roads) without depending on their
+// tile server: OsmAnd's terms restrict tile use to "personal, non-commercial
+// use within OsmAnd applications and platforms", which this app isn't.
+//
+// One shared palette drives two independent recolorings so Online and
+// Offline look consistent: OpenFreeMap's "liberty" vector style (paint
+// colors patched in place, see recolorLayer) for Online, and a custom
+// protomaps-themes-base Theme (see offlineTheme) for Offline.
+
+const PALETTE = {
+  background: "#f1ecd7",
+  water: "#aad3df",
+  wood: "#c8dfb0",
+  park: "#d3e8b8",
+  landuse: "#ece4c6",
+  building: "#d9cead",
+  buildingOutline: "#c7bb92",
+  roadMajor: "#eb9d43",
+  roadMajorCasing: "#c9822c",
+  roadMinor: "#fdf8ee",
+  roadMinorCasing: "#cfc09a",
+  boundary: "#a98fc2",
+};
+
+const LIBERTY_STYLE_URL = "https://tiles.openfreemap.org/styles/liberty";
+let cachedOnlineStyle = null;
+
+// Fetches OpenFreeMap's "liberty" style and recolors it in place. Cached —
+// the recoloring is pure, and re-fetching on every Online/Offline toggle
+// would be wasteful.
+export async function onlineStyle() {
+  if (cachedOnlineStyle) return cachedOnlineStyle;
+
+  const response = await fetch(LIBERTY_STYLE_URL);
+  const style = await response.json();
+  style.layers = style.layers.map(recolorLayer);
+  cachedOnlineStyle = style;
+  return style;
+}
+
+// Overrides the color roles that define the "look" on top of a
+// protomaps-themes-base Theme (e.g. namedTheme("light")), leaving roles it
+// doesn't set (labels, rail, tunnels, POI colors) at their defaults.
+export function offlineTheme(baseTheme) {
+  return {
+    ...baseTheme,
+    background: PALETTE.background,
+    earth: PALETTE.background,
+    water: PALETTE.water,
+    wood_a: PALETTE.wood,
+    wood_b: PALETTE.wood,
+    park_a: PALETTE.park,
+    park_b: PALETTE.park,
+    scrub_a: PALETTE.park,
+    scrub_b: PALETTE.park,
+    pedestrian: PALETTE.landuse,
+    industrial: PALETTE.landuse,
+    school: PALETTE.landuse,
+    hospital: PALETTE.landuse,
+    buildings: PALETTE.building,
+    highway_casing_early: PALETTE.roadMajorCasing,
+    highway_casing_late: PALETTE.roadMajorCasing,
+    highway: PALETTE.roadMajor,
+    major_casing_early: PALETTE.roadMajorCasing,
+    major_casing_late: PALETTE.roadMajorCasing,
+    major: PALETTE.roadMajor,
+    link_casing: PALETTE.roadMajorCasing,
+    link: PALETTE.roadMajor,
+    minor_casing: PALETTE.roadMinorCasing,
+    minor_service_casing: PALETTE.roadMinorCasing,
+    minor_a: PALETTE.roadMinor,
+    minor_b: PALETTE.roadMinor,
+    other: PALETTE.roadMinor,
+    minor_service: PALETTE.roadMinor,
+    boundaries: PALETTE.boundary,
+  };
+}
+
+const FILL_PROP = /^(background-color|fill-color|line-color|fill-extrusion-color)$/;
+const OUTLINE_PROP = /outline-color$/;
+
+const FILL_COLOR = {
+  background: PALETTE.background,
+  water: PALETTE.water,
+  wood: PALETTE.wood,
+  park: PALETTE.park,
+  landuse: PALETTE.landuse,
+  building: PALETTE.building,
+  roadMajor: PALETTE.roadMajor,
+  roadMinor: PALETTE.roadMinor,
+  boundary: PALETTE.boundary,
+};
+
+const OUTLINE_COLOR = {
+  building: PALETTE.buildingOutline,
+  roadMajor: PALETTE.roadMajorCasing,
+  roadMinor: PALETTE.roadMinorCasing,
+  park: "#bcdb9a",
+};
+
+// Maps a "liberty" style layer id to one of the categories above, based on
+// the id naming conventions OpenFreeMap's style uses (verified against its
+// actual layer list — see docs/architecture.adoc). Returns null for
+// anything left at its original color: labels/icons (all "symbol" layers,
+// filtered by type below before this even runs), railways, and minor
+// terrain fills (ice/wetland/sand) that aren't part of OsmAnd's signature
+// look.
+function categoryFor(layerId) {
+  if (layerId === "background") return "background";
+  if (/rail/.test(layerId)) return null;
+  if (/^water/.test(layerId)) return "water";
+  if (/^landcover_wood/.test(layerId)) return "wood";
+  if (/^(park|landcover_grass)/.test(layerId)) return "park";
+  if (/^landuse/.test(layerId)) return "landuse";
+  if (/^building/.test(layerId)) return "building";
+  if (/^(road|bridge|tunnel)_(motorway|trunk_primary)/.test(layerId)) return "roadMajor";
+  if (/^(road|bridge|tunnel)_/.test(layerId)) return "roadMinor";
+  if (/^boundary/.test(layerId)) return "boundary";
+  return null;
+}
+
+const RECOLORABLE_TYPES = new Set(["background", "fill", "line", "fill-extrusion"]);
+
+function recolorLayer(layer) {
+  if (!RECOLORABLE_TYPES.has(layer.type) || !layer.paint) return layer;
+
+  const category = categoryFor(layer.id);
+  if (!category) return layer;
+
+  const paint = { ...layer.paint };
+  for (const [prop, value] of Object.entries(paint)) {
+    if (OUTLINE_PROP.test(prop) && OUTLINE_COLOR[category]) {
+      paint[prop] = replaceColors(value, OUTLINE_COLOR[category]);
+    } else if (FILL_PROP.test(prop)) {
+      paint[prop] = replaceColors(value, FILL_COLOR[category]);
+    }
+  }
+
+  return { ...layer, paint };
+}
+
+const COLOR_PATTERN = /^#[0-9a-f]{3,8}$/i;
+const COLOR_FN_PATTERN = /^(rgb|hsl)a?\(/i;
+
+// Walks a paint value — a flat color string, or a MapLibre expression like
+// ["interpolate", ["linear"], ["zoom"], 5, "hsl(26,87%,62%)", 6, "#fc8"] —
+// and swaps every color-shaped string for `newColor`, leaving operators,
+// zoom/get references and numbers untouched. Generic across expression
+// types (interpolate/match/case/step/...) since it never inspects the
+// expression's operator, only whether each leaf looks like a color.
+function replaceColors(value, newColor) {
+  if (typeof value === "string") {
+    return COLOR_PATTERN.test(value) || COLOR_FN_PATTERN.test(value) ? newColor : value;
+  }
+  if (Array.isArray(value)) {
+    return value.map((item) => replaceColors(item, newColor));
+  }
+  return value;
+}

public/js/panels.js

@@ -0,0 +1,17 @@
+// Keeps at most one full-height side panel (base map, GPX, ...) open at a
+// time — they all dock to the same spot next to the sidebar, so two open
+// together would just stack on top of each other.
+const OPEN_EVENT = "side-panel-open";
+
+export function notifySidePanelOpen(panel) {
+  document.dispatchEvent(new CustomEvent(OPEN_EVENT, { detail: panel }));
+}
+
+export function onlyOneSidePanelOpen(panel, onClosedByOther) {
+  document.addEventListener(OPEN_EVENT, (event) => {
+    if (event.detail !== panel && !panel.hidden) {
+      panel.hidden = true;
+      onClosedByOther();
+    }
+  });
+}

public/js/radar.js

@@ -1,3 +1,5 @@
+import { RADAR_ICON } from "/js/icons.js";
+
 const RAINVIEWER_API = "https://api.rainviewer.com/public/weather-maps.json";
 
 // Matches the default window used by github.com/jpettitt/weather-radar-card
@@ -9,10 +11,10 @@ const OPACITY = 0.7;
 const ATTRIBUTION =
   'Weather data &copy; <a href="https://www.rainviewer.com" target="_blank">RainViewer</a>';
 
-// A MapLibre IControl: a "Radar" checkbox that fetches RainViewer's recent
-// precipitation frames on demand and animates them as a raster overlay, with
-// play/pause and a scrub slider. No API key needed — see
-// docs/architecture.adoc for RainViewer's usage terms.
+// A sidebar icon that fetches RainViewer's recent precipitation frames on
+// demand and animates them as a raster overlay, with play/pause and a scrub
+// slider in a flyout. No API key needed — see docs/architecture.adoc for
+// RainViewer's usage terms.
 export class RadarControl {
   constructor(map) {
     this._map = map;
@@ -29,45 +31,39 @@ export class RadarControl {
     });
   }
 
-  onAdd() {
+  mount(sidebar) {
     this._container = document.createElement("div");
-    this._container.className = "maplibregl-ctrl maplibregl-ctrl-group radar-control";
+    this._container.className = "sidebar-item";
     this._container.innerHTML = `
-      <label class="radar-control__toggle">
-        <input type="checkbox" class="radar-control__checkbox">
-        Radar
-      </label>
-      <div class="radar-control__playback" hidden>
+      <button type="button" class="sidebar-icon" title="Radar" aria-label="Radar">${RADAR_ICON}</button>
+      <div class="sidebar-flyout" hidden>
+        <div class="radar-control__playback">
           <button type="button" class="radar-control__play" aria-label="Play">&#9654;</button>
           <input type="range" class="radar-control__scrub" min="0" max="0" step="1" value="0">
           <span class="radar-control__time"></span>
         </div>
+      </div>
     `;
 
-    this._checkbox = this._container.querySelector(".radar-control__checkbox");
-    this._playback = this._container.querySelector(".radar-control__playback");
+    this._icon = this._container.querySelector(".sidebar-icon");
+    this._flyout = this._container.querySelector(".sidebar-flyout");
     this._playButton = this._container.querySelector(".radar-control__play");
     this._scrub = this._container.querySelector(".radar-control__scrub");
     this._time = this._container.querySelector(".radar-control__time");
 
-    this._checkbox.addEventListener("change", () => this._setEnabled(this._checkbox.checked));
+    this._icon.addEventListener("click", () => this._setEnabled(!this._enabled));
     this._playButton.addEventListener("click", () => this._togglePlayback());
     this._scrub.addEventListener("input", () => {
       this._stopAnimation();
       this._showFrame(Number(this._scrub.value));
     });
 
-    return this._container;
-  }
-
-  onRemove() {
-    this._stopAnimation();
-    this._removeLayers();
-    this._container.remove();
+    sidebar.appendChild(this._container);
   }
 
   async _setEnabled(enabled) {
     this._enabled = enabled;
+    this._icon.classList.toggle("active", enabled);
     if (!enabled) {
       this._stopAnimation();
       this._removeLayers();
@@ -76,20 +72,20 @@ export class RadarControl {
       return;
     }
 
-    this._checkbox.disabled = true;
+    this._icon.disabled = true;
     let frames;
     try {
       frames = await fetchFrames();
     } catch (err) {
       this._enabled = false;
-      this._checkbox.checked = false;
-      this._checkbox.disabled = false;
+      this._icon.classList.remove("active");
+      this._icon.disabled = false;
       return;
     }
-    this._checkbox.disabled = false;
+    this._icon.disabled = false;
 
-    // The checkbox may have been switched off again while the fetch was in
-    // flight.
+    // The icon may have been clicked again (disabling) while the fetch was
+    // in flight.
     if (!this._enabled || !frames.length) return;
 
     this._frames = frames;
@@ -168,7 +164,7 @@ export class RadarControl {
   }
 
   _updateFrameUI() {
-    this._playback.hidden = this._frames.length === 0;
+    this._flyout.hidden = this._frames.length === 0;
     this._scrub.max = String(Math.max(0, this._frames.length - 1));
     this._scrub.value = String(this._frameIndex);
     const frame = this._frames[this._frameIndex];

views/index.erb

@@ -1,21 +1,43 @@
-<div id="map"></div>
+<div id="app">
+  <header class="topbar">
+    <span class="topbar__brand">MapTool</span>
+  </header>
+
+  <div class="app-body">
+    <nav id="sidebar" class="sidebar"></nav>
+    <div id="map"></div>
+  </div>
+</div>
+
+<div id="basemap-panel" class="basemap-panel" hidden>
+  <div class="basemap-panel__header">
+    <strong>Base map</strong>
+    <button type="button" class="basemap-panel__close" aria-label="Close">&times;</button>
+  </div>
+  <div class="basemap-panel__list">
+    <button type="button" class="basemap-panel__option" data-style="online">
+      <span>Online</span>
+      <span class="basemap-panel__check">&check;</span>
+    </button>
+    <button type="button" class="basemap-panel__option" data-style="offline">
+      <span>Offline</span>
+      <span class="basemap-panel__check">&check;</span>
+    </button>
+  </div>
+</div>
 
 <div id="gpx-panel" class="gpx-panel" hidden>
   <div class="gpx-panel__header">
     <strong>GPX</strong>
+    <div class="gpx-panel__actions">
+      <button type="button" class="gpx-panel__action" data-action="new-folder" title="New folder" aria-label="New folder"></button>
+      <button type="button" class="gpx-panel__action" data-action="upload" title="Upload GPX file" aria-label="Upload GPX file"></button>
       <button type="button" class="gpx-panel__close" aria-label="Close">&times;</button>
     </div>
-
-  <div class="gpx-dropzone">
-    Drop .gpx files here, or click to browse
-    <input type="file" class="gpx-dropzone__input" accept=".gpx" multiple hidden>
   </div>
-  <p class="gpx-upload__status" hidden></p>
 
-  <form class="gpx-new-folder">
-    <input type="text" name="path" placeholder="new folder path (e.g. Hiking/2026)">
-    <button type="submit">+ folder</button>
-  </form>
+  <input type="file" class="gpx-file-input" accept=".gpx" multiple hidden>
+  <p class="gpx-upload__status" hidden></p>
 
   <div class="gpx-tree"></div>
 </div>