diff --git a/README.md b/README.md
index 80696b3..a56fa13 100644
--- a/README.md
+++ b/README.md
@@ -99,6 +99,7 @@ with this machine's shell settings — the same keys as the checked-in
 | --- | --- |
 | `port` | Port ProdDash serves on (default `24500`). The macOS launcher writes this one, so the port it is set to holds however ProdDash is started. |
 | `adminPasscode` | If set, the admin page asks for this shared passcode. Leave `""` for none — it's a plain-HTTP LAN tool. |
+| `theme` | The dashboard palette: `booth` (default), `harbor`, `graphite`, `ember` or `daylight`. The admin page's **Theme** section writes this one — see [Themes](#themes). |
 
 Environment variables override both files: `PORT`, `PRODDASH_PASSCODE`, and
 `PRODDASH_DATA_DIR` to put the data directory somewhere else (a relative path
@@ -111,6 +112,22 @@ so and falls back to the app's `config/` folder.
 directory, so nothing has to be re-entered. The old files are left in place and
 ignored from then on.
 
+### Themes
+
+The whole dashboard — every tile, on every browser — draws with one palette,
+chosen in the admin page's **Theme** section and switched live: pick a swatch
+and open dashboards change without a reload. Five presets ship: **Booth**
+(the default dark, mint accent), **Harbor** (deep navy, cyan), **Graphite**
+(neutral charcoal, electric blue), **Ember** (warm broadcast black, orange)
+and **Daylight**, a light palette for a front-of-house desk in daytime. Each
+keeps the status colours apart — the accent is never near the danger red or
+the warning amber — and muted text readable in a dark booth. The choice is
+stored as `theme` in the data directory's `proddash.json` (table above), so
+it holds across restarts and updates; a browser remembers the last theme it
+saw and applies it before the server answers, so nothing flashes. Modules
+style with the shell's colour variables, which is why they follow; a colour
+set on a tile itself (a PCO Plan header colour, say) is deliberately kept.
+
 ## Installing modules and updating
 
 Everything below happens in the **admin page**; ProdDash talks to its GitHub
diff --git a/public/shell.js b/public/shell.js
index 5a8fc98..454dc4a 100644
--- a/public/shell.js
+++ b/public/shell.js
@@ -1381,6 +1381,7 @@ function subscribeEvents() {
   try { eventsSource?.close(); } catch { /* not open */ }
   eventsSource = new EventSource('/api/events');
   eventsSource.addEventListener('modules-changed', () => handleModulesChanged());
+  eventsSource.addEventListener('theme', handleThemeEvent);
   eventsSource.onerror = () => {
     if (eventsSource.readyState === EventSource.CLOSED) {
       clearTimeout(eventsRetry);
@@ -1417,6 +1418,43 @@ async function handleModulesChanged() {
   }
 }
 
+/* ── theme ──────────────────────────────────────────────────────────── */
+
+/* The dashboard's palette is a server-wide choice (Admin → Theme). Five
+   preset variable sets live in style.css as html[data-theme="…"]; applying
+   one is setting that attribute. The last-known theme goes on synchronously
+   from localStorage so a reload never flashes the default palette, then the
+   server's answer (GET /api/theme) wins, and a `theme` shell event on
+   /api/events switches every open dashboard the moment an admin picks
+   another. Modules style with the shell variables, so they follow; a colour
+   a tile is configured with is set on the tile itself and stays as chosen. */
+
+const LS_THEME = 'proddash:theme';
+
+function applyTheme(id) {
+  const theme = String(id || '');
+  if (!/^[a-z][a-z0-9-]{0,31}$/.test(theme)) return;
+  document.documentElement.dataset.theme = theme;
+  try { localStorage.setItem(LS_THEME, theme); } catch { /* private mode — fine */ }
+}
+
+/** `theme` shell event from /api/events (wired in subscribeEvents). */
+function handleThemeEvent(e) {
+  try {
+    applyTheme(JSON.parse(e.data).theme);
+  } catch { /* a malformed frame changes nothing */ }
+}
+
+function initTheme() {
+  try { applyTheme(localStorage.getItem(LS_THEME)); } catch { /* fine */ }
+  fetch('/api/theme', { cache: 'no-store' })
+    .then((res) => (res.ok ? res.json() : null))
+    .then((body) => { if (body?.theme) applyTheme(body.theme); })
+    .catch(() => { /* offline: the remembered theme stands */ });
+}
+
+initTheme();
+
 /* ── boot ───────────────────────────────────────────────────────────── */
 
 async function boot() {
diff --git a/public/style.css b/public/style.css
index 2ff8649..e8c03a7 100644
--- a/public/style.css
+++ b/public/style.css
@@ -755,3 +755,63 @@ body.fullscreen #grid { padding-bottom: 0; }
 @media (max-width: 560px) {
   #topbar { padding: 0 8px; gap: 6px; }
 }
+
+/* ── themes ────────────────────────────────────────────────────────── */
+
+/* Preset palettes, chosen in Admin → Theme and applied by shell.js (and the
+   admin page) as html[data-theme="…"]. Each swaps exactly the eight palette
+   variables the module guide names — nothing else — so every module and
+   every shell element follows, and a colour a tile is configured with (set
+   on the tile itself) still wins. The :root block at the top of this file is
+   "booth", the default; the list of ids and names lives in server.js
+   (GET /api/theme). All four are booth-grade: high contrast, the accent
+   nowhere near the danger red or the warning amber, muted still readable. */
+
+/* Harbor — deep navy, cyan accent */
+html[data-theme="harbor"] {
+  --bg: #06101f;
+  --panel: #0c1a30;
+  --border: #1a2b48;
+  --text: #e6eefb;
+  --muted: #8ea4c8;
+  --accent: #2ad4ee;
+  --danger: #ff5a5f;
+  --warn: #f7b53b;
+}
+
+/* Graphite — neutral charcoal, electric-blue accent */
+html[data-theme="graphite"] {
+  --bg: #0f1012;
+  --panel: #17191d;
+  --border: #2a2d33;
+  --text: #f0f2f4;
+  --muted: #9ca3ad;
+  --accent: #6cb4ff;
+  --danger: #ff4d4f;
+  --warn: #ffb224;
+}
+
+/* Ember — warm broadcast black, orange accent (danger stays a cool red,
+   warn a pale yellow, so the three status colours never blur) */
+html[data-theme="ember"] {
+  --bg: #120c0a;
+  --panel: #1d1411;
+  --border: #35251e;
+  --text: #f6ede6;
+  --muted: #b39b8c;
+  --accent: #ff8f3a;
+  --danger: #f03247;
+  --warn: #ffd86b;
+}
+
+/* Daylight — the light one, for a front-of-house desk in daytime */
+html[data-theme="daylight"] {
+  --bg: #eef1f5;
+  --panel: #ffffff;
+  --border: #cfd6e0;
+  --text: #14181f;
+  --muted: #5b6675;
+  --accent: #0b8a5f;
+  --danger: #d1242f;
+  --warn: #b26a00;
+}
diff --git a/server.js b/server.js
index 5655907..5652f06 100644
--- a/server.js
+++ b/server.js
@@ -541,6 +541,60 @@ setInterval(() => {
   }
 }, 25000).unref();
 
+/* ── themes ─────────────────────────────────────────────────────────── */
+
+/* Preset palettes for the whole dashboard, chosen in Admin → Theme. The
+   variable sets themselves live in public/style.css (html[data-theme="…"]);
+   this list is the one authority on ids and names, and carries the three
+   colours the admin page previews a theme with. The choice is a shell
+   setting — `theme` in the data directory's proddash.json — and reaches open
+   dashboards live as a `theme` shell event. */
+const THEMES = [
+  { id: 'booth',    name: 'Booth',    colors: { bg: '#0b0e12', panel: '#131920', accent: '#2ee59a' } },
+  { id: 'harbor',   name: 'Harbor',   colors: { bg: '#06101f', panel: '#0c1a30', accent: '#2ad4ee' } },
+  { id: 'graphite', name: 'Graphite', colors: { bg: '#0f1012', panel: '#17191d', accent: '#6cb4ff' } },
+  { id: 'ember',    name: 'Ember',    colors: { bg: '#120c0a', panel: '#1d1411', accent: '#ff8f3a' } },
+  { id: 'daylight', name: 'Daylight', colors: { bg: '#eef1f5', panel: '#ffffff', accent: '#0b8a5f' } },
+];
+const DEFAULT_THEME = THEMES[0].id;
+
+function themeExists(id) {
+  return THEMES.some((t) => t.id === id);
+}
+
+let currentTheme = themeExists(shellConfig.theme) ? shellConfig.theme : DEFAULT_THEME;
+
+/** What GET /api/theme returns — public, since dashboards need it before anyone logs in. */
+function themeView() {
+  return {
+    theme: currentTheme,
+    themes: THEMES.map((t) => ({ id: t.id, name: t.name, colors: { ...t.colors } })),
+  };
+}
+
+/**
+ * Persist the theme into this machine's proddash.json (every other key there
+ * — port, adminPasscode, repo… — is kept), remember it, and tell every open
+ * dashboard and admin page. Throws an httpError for an unknown id or an
+ * unreadable settings file; the route turns that into the response.
+ */
+function setTheme(id) {
+  if (!themeExists(id)) throw httpError(400, `Unknown theme "${id}".`);
+  const file = path.join(DATA_DIR, 'proddash.json');
+  let existing = {};
+  if (fs.existsSync(file)) {
+    existing = readJson(file, null);
+    if (!existing || typeof existing !== 'object' || Array.isArray(existing)) {
+      throw httpError(500, `${file} is not a JSON object — fix it by hand before changing the theme.`);
+    }
+  }
+  writeJson(file, { ...existing, theme: id });
+  currentTheme = id;
+  shellConfig.theme = id;
+  broadcastShellEvent('theme', { theme: id });
+  return themeView();
+}
+
 /* ── the repo: module catalog and shell updates ──────────────────────── */
 
 /* The admin page installs modules from, and updates the shell against, the
@@ -1109,6 +1163,22 @@ async function handleAdminApi(req, res, urlPath) {
     return sendJson(res, 200, { ok: true, module: adminModuleView(id) });
   }
 
+  /* — theme: { "theme": "<id>" }, validated against THEMES — */
+  if (urlPath === '/api/admin/theme' && req.method === 'POST') {
+    if (refuseAdminWrite(req, res)) return;
+    let body = {};
+    try {
+      body = JSON.parse((await readBody(req)) || '{}');
+    } catch {
+      return sendJson(res, 400, { error: 'Malformed request.' });
+    }
+    try {
+      return sendJson(res, 200, { ok: true, ...setTheme(String(body.theme ?? '')) });
+    } catch (err) {
+      return sendJson(res, err.status || 500, { error: err.message || String(err) });
+    }
+  }
+
   sendJson(res, 404, { error: 'Unknown admin endpoint.' });
 }
 
@@ -1352,6 +1422,11 @@ function handleRequest(req, res) {
     return;
   }
 
+  /* — theme: public (dashboards need it without a passcode); changed via POST /api/admin/theme — */
+  if (urlPath === '/api/theme' && req.method === 'GET') {
+    return sendJson(res, 200, themeView());
+  }
+
   /* — shell events: open dashboards learn about admin changes live — */
   if (urlPath === '/api/events' && req.method === 'GET') {
     res.writeHead(200, {