diff --git a/ui/src/app.css b/ui/src/app.css
index 8ad22ac..d5e1cb8 100644
--- a/ui/src/app.css
+++ b/ui/src/app.css
@@ -250,6 +250,52 @@ html {
 	animation: progress-bar 4s cubic-bezier(0.1, 0.05, 0.1, 1) forwards;
 }
 
+/* ── Logo animation classes (used in nav + admin preview) ───────────── */
+@keyframes logo-glow-pulse {
+	0%, 100% { text-shadow: 0 0 6px color-mix(in srgb, var(--color-brand) 60%, transparent); }
+	50%       { text-shadow: 0 0 18px color-mix(in srgb, var(--color-brand) 90%, transparent), 0 0 32px color-mix(in srgb, var(--color-brand) 40%, transparent); }
+}
+.logo-anim-glow {
+	animation: logo-glow-pulse 2.4s ease-in-out infinite;
+}
+
+@keyframes logo-shimmer {
+	0%   { background-position: -200% center; }
+	100% { background-position: 200% center; }
+}
+.logo-anim-shimmer {
+	background: linear-gradient(
+		90deg,
+		var(--color-brand) 0%,
+		color-mix(in srgb, var(--color-brand) 40%, white) 40%,
+		var(--color-brand) 50%,
+		color-mix(in srgb, var(--color-brand) 40%, white) 60%,
+		var(--color-brand) 100%
+	);
+	background-size: 200% auto;
+	background-clip: text;
+	-webkit-background-clip: text;
+	-webkit-text-fill-color: transparent;
+	animation: logo-shimmer 2.2s linear infinite;
+}
+
+@keyframes logo-pulse-scale {
+	0%, 100% { transform: scale(1); }
+	50%       { transform: scale(1.06); }
+}
+.logo-anim-pulse {
+	display: inline-block;
+	animation: logo-pulse-scale 1.8s ease-in-out infinite;
+}
+
+@keyframes logo-rainbow {
+	0%   { filter: hue-rotate(0deg);   }
+	100% { filter: hue-rotate(360deg); }
+}
+.logo-anim-rainbow {
+	animation: logo-rainbow 4s linear infinite;
+}
+
 /* ── Respect reduced motion — disable all decorative animations ─────── */
 @media (prefers-reduced-motion: reduce) {
 	*,
diff --git a/ui/src/lib/components/SeasonalDecoration.svelte b/ui/src/lib/components/SeasonalDecoration.svelte
new file mode 100644
index 0000000..e6b498e
--- /dev/null
+++ b/ui/src/lib/components/SeasonalDecoration.svelte
@@ -0,0 +1,285 @@
+<script lang="ts">
+	/**
+	 * SeasonalDecoration — full-viewport canvas particle overlay.
+	 *
+	 * Modes:
+	 *   snow       — white circular snowflakes drifting down with gentle sway
+	 *   sakura     — pink/white ellipse petals falling and rotating
+	 *   fireflies  — small glowing dots floating up, pulsing opacity
+	 *   leaves     — orange/red/yellow tear-drop shapes tumbling down
+	 *   stars      — white stars twinkling in place (fixed positions, opacity animation)
+	 */
+
+	type Mode = 'snow' | 'sakura' | 'fireflies' | 'leaves' | 'stars';
+
+	interface Props { mode: Mode }
+	let { mode }: Props = $props();
+
+	let canvas = $state<HTMLCanvasElement | null>(null);
+	let raf = 0;
+
+	// ── Particle types ──────────────────────────────────────────────────────
+
+	interface Particle {
+		x: number; y: number; r: number;
+		vx: number; vy: number;
+		angle: number; vAngle: number;
+		opacity: number; vOpacity: number;
+		color: string;
+		// star-specific
+		twinkleOffset?: number;
+	}
+
+	// ── Palette helpers ──────────────────────────────────────────────────────
+
+	function rand(min: number, max: number) { return min + Math.random() * (max - min); }
+	function randInt(min: number, max: number) { return Math.floor(rand(min, max + 1)); }
+
+	const SNOW_COLORS    = ['rgba(255,255,255,0.85)', 'rgba(200,220,255,0.75)', 'rgba(220,235,255,0.8)'];
+	const SAKURA_COLORS  = ['rgba(255,182,193,0.85)', 'rgba(255,200,210,0.8)', 'rgba(255,240,245,0.9)', 'rgba(255,160,180,0.75)'];
+	const FIREFLY_COLORS = ['rgba(180,255,100,0.9)', 'rgba(220,255,150,0.85)', 'rgba(255,255,180,0.8)'];
+	const LEAF_COLORS    = ['rgba(210,80,20,0.85)', 'rgba(190,120,30,0.8)', 'rgba(220,160,40,0.85)', 'rgba(180,60,10,0.8)', 'rgba(240,140,30,0.9)'];
+	const STAR_COLORS    = ['rgba(255,255,255,0.9)', 'rgba(255,240,180,0.85)', 'rgba(180,210,255,0.8)'];
+
+	// ── Spawn helpers ────────────────────────────────────────────────────────
+
+	function spawnSnow(W: number, H: number): Particle {
+		return {
+			x: rand(0, W), y: rand(-H * 0.2, -4),
+			r: rand(1.5, 5),
+			vx: rand(-0.4, 0.4), vy: rand(0.6, 2.0),
+			angle: 0, vAngle: 0,
+			opacity: rand(0.5, 1), vOpacity: 0,
+			color: SNOW_COLORS[randInt(0, SNOW_COLORS.length - 1)],
+		};
+	}
+
+	function spawnSakura(W: number, H: number): Particle {
+		return {
+			x: rand(0, W), y: rand(-H * 0.2, -4),
+			r: rand(3, 7),
+			vx: rand(-0.6, 0.6), vy: rand(0.5, 1.6),
+			angle: rand(0, Math.PI * 2), vAngle: rand(-0.03, 0.03),
+			opacity: rand(0.6, 1), vOpacity: 0,
+			color: SAKURA_COLORS[randInt(0, SAKURA_COLORS.length - 1)],
+		};
+	}
+
+	function spawnFirefly(W: number, H: number): Particle {
+		return {
+			x: rand(0, W), y: rand(H * 0.3, H),
+			r: rand(1.5, 3.5),
+			vx: rand(-0.3, 0.3), vy: rand(-0.8, -0.2),
+			angle: 0, vAngle: 0,
+			opacity: rand(0.2, 0.8), vOpacity: rand(0.008, 0.025) * (Math.random() < 0.5 ? 1 : -1),
+			color: FIREFLY_COLORS[randInt(0, FIREFLY_COLORS.length - 1)],
+		};
+	}
+
+	function spawnLeaf(W: number, H: number): Particle {
+		return {
+			x: rand(0, W), y: rand(-H * 0.2, -4),
+			r: rand(4, 9),
+			vx: rand(-1.2, 1.2), vy: rand(0.8, 2.5),
+			angle: rand(0, Math.PI * 2), vAngle: rand(-0.05, 0.05),
+			opacity: rand(0.6, 1), vOpacity: 0,
+			color: LEAF_COLORS[randInt(0, LEAF_COLORS.length - 1)],
+		};
+	}
+
+	function spawnStar(W: number, H: number): Particle {
+		return {
+			x: rand(0, W), y: rand(0, H),
+			r: rand(0.8, 2.5),
+			vx: 0, vy: 0,
+			angle: 0, vAngle: 0,
+			opacity: rand(0.1, 0.9),
+			vOpacity: rand(0.004, 0.015) * (Math.random() < 0.5 ? 1 : -1),
+			color: STAR_COLORS[randInt(0, STAR_COLORS.length - 1)],
+			twinkleOffset: rand(0, Math.PI * 2),
+		};
+	}
+
+	// ── Draw helpers ─────────────────────────────────────────────────────────
+
+	function drawSnow(ctx: CanvasRenderingContext2D, p: Particle) {
+		ctx.beginPath();
+		ctx.arc(p.x, p.y, p.r, 0, Math.PI * 2);
+		ctx.fillStyle = p.color;
+		ctx.globalAlpha = p.opacity;
+		ctx.fill();
+	}
+
+	function drawSakura(ctx: CanvasRenderingContext2D, p: Particle) {
+		ctx.save();
+		ctx.translate(p.x, p.y);
+		ctx.rotate(p.angle);
+		ctx.beginPath();
+		ctx.ellipse(0, 0, p.r * 1.8, p.r, 0, 0, Math.PI * 2);
+		ctx.fillStyle = p.color;
+		ctx.globalAlpha = p.opacity;
+		ctx.fill();
+		ctx.restore();
+	}
+
+	function drawFirefly(ctx: CanvasRenderingContext2D, p: Particle) {
+		// Glow effect: large soft circle + small bright core
+		const grd = ctx.createRadialGradient(p.x, p.y, 0, p.x, p.y, p.r * 4);
+		grd.addColorStop(0, p.color);
+		grd.addColorStop(1, 'rgba(0,0,0,0)');
+		ctx.beginPath();
+		ctx.arc(p.x, p.y, p.r * 4, 0, Math.PI * 2);
+		ctx.fillStyle = grd;
+		ctx.globalAlpha = p.opacity * 0.6;
+		ctx.fill();
+		ctx.beginPath();
+		ctx.arc(p.x, p.y, p.r, 0, Math.PI * 2);
+		ctx.fillStyle = p.color;
+		ctx.globalAlpha = p.opacity;
+		ctx.fill();
+	}
+
+	function drawLeaf(ctx: CanvasRenderingContext2D, p: Particle) {
+		ctx.save();
+		ctx.translate(p.x, p.y);
+		ctx.rotate(p.angle);
+		ctx.beginPath();
+		ctx.moveTo(0, -p.r * 1.5);
+		ctx.bezierCurveTo(p.r * 1.2, -p.r * 0.5, p.r * 1.2, p.r * 0.5, 0, p.r * 1.5);
+		ctx.bezierCurveTo(-p.r * 1.2, p.r * 0.5, -p.r * 1.2, -p.r * 0.5, 0, -p.r * 1.5);
+		ctx.fillStyle = p.color;
+		ctx.globalAlpha = p.opacity;
+		ctx.fill();
+		ctx.restore();
+	}
+
+	function drawStar(ctx: CanvasRenderingContext2D, p: Particle, t: number) {
+		const pulse = 0.5 + 0.5 * Math.sin(t * 0.002 + (p.twinkleOffset ?? 0));
+		ctx.beginPath();
+		ctx.arc(p.x, p.y, p.r, 0, Math.PI * 2);
+		ctx.fillStyle = p.color;
+		ctx.globalAlpha = p.opacity * pulse;
+		ctx.fill();
+	}
+
+	// ── Particle count by mode ────────────────────────────────────────────────
+
+	const COUNT: Record<Mode, number> = {
+		snow: 120, sakura: 60, fireflies: 50, leaves: 45, stars: 150,
+	};
+
+	// ── Main effect ──────────────────────────────────────────────────────────
+
+	$effect(() => {
+		if (!canvas) return;
+		const ctx = canvas.getContext('2d');
+		if (!ctx) return;
+
+		let W = window.innerWidth;
+		let H = window.innerHeight;
+		canvas.width = W;
+		canvas.height = H;
+
+		const onResize = () => {
+			W = window.innerWidth;
+			H = window.innerHeight;
+			canvas!.width = W;
+			canvas!.height = H;
+			// Reseed stars on resize since they're positionally fixed
+			if (mode === 'stars') {
+				particles.length = 0;
+				for (let i = 0; i < COUNT.stars; i++) particles.push(spawnStar(W, H));
+			}
+		};
+		window.addEventListener('resize', onResize);
+
+		const n = COUNT[mode];
+		const particles: Particle[] = [];
+
+		// Pre-scatter initial particles across the full height
+		for (let i = 0; i < n; i++) {
+			let p: Particle;
+			switch (mode) {
+				case 'snow':       p = spawnSnow(W, H);      p.y = rand(0, H); break;
+				case 'sakura':     p = spawnSakura(W, H);    p.y = rand(0, H); break;
+				case 'fireflies':  p = spawnFirefly(W, H);                     break;
+				case 'leaves':     p = spawnLeaf(W, H);      p.y = rand(0, H); break;
+				case 'stars':      p = spawnStar(W, H);                        break;
+			}
+			particles.push(p);
+		}
+
+		let t = 0;
+
+		function tick() {
+			ctx!.clearRect(0, 0, W, H);
+			ctx!.save();
+
+			for (let i = 0; i < particles.length; i++) {
+				const p = particles[i];
+
+				switch (mode) {
+					case 'snow': {
+						// Gentle horizontal sway
+						p.vx = Math.sin(t * 0.001 + p.y * 0.01) * 0.5;
+						p.x += p.vx; p.y += p.vy;
+						if (p.y > H + 10) particles[i] = spawnSnow(W, H);
+						else drawSnow(ctx!, p);
+						break;
+					}
+					case 'sakura': {
+						p.vx = Math.sin(t * 0.0008 + p.y * 0.008) * 0.8;
+						p.x += p.vx; p.y += p.vy;
+						p.angle += p.vAngle;
+						if (p.y > H + 20) particles[i] = spawnSakura(W, H);
+						else drawSakura(ctx!, p);
+						break;
+					}
+					case 'fireflies': {
+						p.x += p.vx + Math.sin(t * 0.002 + i) * 0.3;
+						p.y += p.vy;
+						p.opacity += p.vOpacity;
+						if (p.opacity >= 1)   { p.opacity = 1;   p.vOpacity *= -1; }
+						if (p.opacity <= 0.1) { p.opacity = 0.1; p.vOpacity *= -1; }
+						if (p.y < -10) particles[i] = spawnFirefly(W, H);
+						else drawFirefly(ctx!, p);
+						break;
+					}
+					case 'leaves': {
+						p.vx = Math.sin(t * 0.001 + p.y * 0.01) * 1.2 + p.vx * 0.02;
+						p.x += p.vx; p.y += p.vy;
+						p.angle += p.vAngle;
+						if (p.y > H + 20) particles[i] = spawnLeaf(W, H);
+						else drawLeaf(ctx!, p);
+						break;
+					}
+					case 'stars': {
+						drawStar(ctx!, p, t);
+						break;
+					}
+				}
+			}
+
+			ctx!.restore();
+			t++;
+			raf = requestAnimationFrame(tick);
+		}
+
+		raf = requestAnimationFrame(tick);
+
+		return () => {
+			cancelAnimationFrame(raf);
+			window.removeEventListener('resize', onResize);
+		};
+	});
+</script>
+
+<!--
+  Fixed full-viewport overlay, pointer-events-none so all clicks pass through.
+  z-index 40 keeps it below the sticky nav (z-50) but above page content.
+-->
+<canvas
+	bind:this={canvas}
+	class="fixed inset-0 z-40 pointer-events-none"
+	aria-hidden="true"
+></canvas>
diff --git a/ui/src/lib/server/pocketbase.ts b/ui/src/lib/server/pocketbase.ts
index f986ec1..d7c4ee0 100644
--- a/ui/src/lib/server/pocketbase.ts
+++ b/ui/src/lib/server/pocketbase.ts
@@ -2498,6 +2498,90 @@ export async function getUserStats(
 	};
 }
 
+// ─── Site Config ─────────────────────────────────────────────────────────────
+//
+// A single singleton record in the `site_config` collection holds global
+// display settings (seasonal decoration, logo animation, etc.).
+// The record is lazily created on first write; reads return safe defaults if
+// the collection/record doesn't exist yet.
+
+export interface SiteConfig {
+	/** Seasonal decoration particle effect: null = off */
+	decoration: 'snow' | 'sakura' | 'fireflies' | 'leaves' | 'stars' | null;
+	/** Special CSS class applied to the nav logo text */
+	logoAnimation: 'none' | 'glow' | 'rainbow' | 'pulse' | 'shimmer';
+	/** Human-readable label for the current event/season shown in a small badge */
+	eventLabel: string;
+}
+
+const SITE_CONFIG_DEFAULTS: SiteConfig = {
+	decoration: null,
+	logoAnimation: 'none',
+	eventLabel: '',
+};
+
+// In-memory short cache so every SSR request doesn't hammer PocketBase
+let _siteConfigCache: { value: SiteConfig; exp: number } | null = null;
+const SITE_CONFIG_CACHE_TTL = 60_000; // 60 seconds
+
+export async function getSiteConfig(): Promise<SiteConfig> {
+	if (_siteConfigCache && Date.now() < _siteConfigCache.exp) {
+		return _siteConfigCache.value;
+	}
+	try {
+		const list = await pbGet<{ items: Array<{ id: string } & SiteConfig> }>(
+			'/api/collections/site_config/records?perPage=1'
+		);
+		const row = list.items?.[0];
+		const value: SiteConfig = row
+			? {
+				decoration: row.decoration ?? null,
+				logoAnimation: row.logoAnimation ?? 'none',
+				eventLabel: row.eventLabel ?? '',
+			}
+			: { ...SITE_CONFIG_DEFAULTS };
+		_siteConfigCache = { value, exp: Date.now() + SITE_CONFIG_CACHE_TTL };
+		return value;
+	} catch {
+		// Collection may not exist yet — return defaults silently
+		return { ...SITE_CONFIG_DEFAULTS };
+	}
+}
+
+export async function saveSiteConfig(patch: Partial<SiteConfig>): Promise<void> {
+	// Bust cache
+	_siteConfigCache = null;
+
+	// Ensure collection exists and find the singleton record
+	let existingId: string | null = null;
+	try {
+		const list = await pbGet<{ items: Array<{ id: string }> }>(
+			'/api/collections/site_config/records?perPage=1'
+		);
+		existingId = list.items?.[0]?.id ?? null;
+	} catch {
+		// Collection doesn't exist yet — create it via PocketBase API
+		await pbPost('/api/collections', {
+			name: 'site_config',
+			type: 'base',
+			fields: [
+				{ name: 'decoration',     type: 'text' },
+				{ name: 'logoAnimation',  type: 'text' },
+				{ name: 'eventLabel',     type: 'text' },
+			],
+		});
+	}
+
+	if (existingId) {
+		await pbPatch(`/api/collections/site_config/records/${existingId}`, patch);
+	} else {
+		await pbPost('/api/collections/site_config/records', {
+			...SITE_CONFIG_DEFAULTS,
+			...patch,
+		});
+	}
+}
+
 // ─── AI Jobs ──────────────────────────────────────────────────────────────────
 
 const AI_JOBS_CACHE_KEY = 'admin:ai_jobs';
diff --git a/ui/src/routes/+layout.server.ts b/ui/src/routes/+layout.server.ts
index 88e3972..f66673b 100644
--- a/ui/src/routes/+layout.server.ts
+++ b/ui/src/routes/+layout.server.ts
@@ -1,6 +1,6 @@
 import { redirect } from '@sveltejs/kit';
 import type { LayoutServerLoad } from './$types';
-import { getSettings } from '$lib/server/pocketbase';
+import { getSettings, getSiteConfig } from '$lib/server/pocketbase';
 import { log } from '$lib/server/logger';
 
 // Routes that are accessible without being logged in
@@ -60,6 +60,11 @@ export const load: LayoutServerLoad = async ({ locals, url, cookies }) => {
 	return {
 		user: locals.user,
 		isPro: locals.isPro,
-		settings
+		settings,
+		siteConfig: await getSiteConfig().catch(() => ({
+			decoration: null as null,
+			logoAnimation: 'none' as const,
+			eventLabel: '',
+		})),
 	};
 };
diff --git a/ui/src/routes/+layout.svelte b/ui/src/routes/+layout.svelte
index 6be4dfe..7eb19a9 100644
--- a/ui/src/routes/+layout.svelte
+++ b/ui/src/routes/+layout.svelte
@@ -14,6 +14,7 @@
 	import ListeningMode from '$lib/components/ListeningMode.svelte';
 	import SearchModal from '$lib/components/SearchModal.svelte';
 	import NotificationsModal from '$lib/components/NotificationsModal.svelte';
+	import SeasonalDecoration from '$lib/components/SeasonalDecoration.svelte';
 	import { fly, fade } from 'svelte/transition';
 
 	let { children, data }: { children: Snippet; data: LayoutData } = $props();
@@ -94,6 +95,20 @@
 	let listeningModeOpen = $state(false);
 	let listeningModeChapters = $state(false);
 
+	// ── Site config (seasonal decoration + logo animation) ──────────────────
+	// svelte-ignore state_referenced_locally
+	let siteDecoration   = $state(data.siteConfig?.decoration   ?? null);
+	// svelte-ignore state_referenced_locally
+	let siteLogoAnim     = $state(data.siteConfig?.logoAnimation ?? 'none');
+	// svelte-ignore state_referenced_locally
+	let siteEventLabel   = $state(data.siteConfig?.eventLabel   ?? '');
+	// Refresh when invalidateAll() re-runs layout load (e.g. after admin saves)
+	$effect(() => {
+		siteDecoration = data.siteConfig?.decoration   ?? null;
+		siteLogoAnim   = data.siteConfig?.logoAnimation ?? 'none';
+		siteEventLabel = data.siteConfig?.eventLabel   ?? '';
+	});
+
 	// Build time formatted in the user's local timezone (populated on mount so
 	// SSR and CSR don't produce a mismatch — SSR renders nothing, hydration fills it in).
 	let buildTimeLocal = $state('');
@@ -522,8 +537,18 @@
 	{/if}
 	<header class="border-b border-(--color-border) bg-(--color-surface) sticky top-0 z-50">
 		<nav class="max-w-6xl mx-auto px-4 h-14 flex items-center gap-6">
-			<a href="/" class="text-(--color-brand) font-bold text-lg tracking-tight hover:text-(--color-brand-dim) shrink-0">
+			<a href="/" class="text-(--color-brand) font-bold text-lg tracking-tight hover:text-(--color-brand-dim) shrink-0 flex items-center gap-1.5
+				{siteLogoAnim === 'glow'    ? 'logo-anim-glow'    : ''}
+				{siteLogoAnim === 'shimmer' ? 'logo-anim-shimmer' : ''}
+				{siteLogoAnim === 'pulse'   ? 'logo-anim-pulse'   : ''}
+				{siteLogoAnim === 'rainbow' ? 'logo-anim-rainbow' : ''}
+			">
 				libnovel
+				{#if siteEventLabel}
+					<span class="text-[10px] font-semibold px-1.5 py-0.5 rounded-full bg-(--color-brand)/15 text-(--color-brand) border border-(--color-brand)/30 leading-none tracking-wide">
+						{siteEventLabel}
+					</span>
+				{/if}
 			</a>
 
 			{#if page.data.book?.title && /\/books\/[^/]+\/chapters\//.test(page.url.pathname)}
@@ -1173,3 +1198,13 @@
 		searchOpen = true;
 	}
 }} />
+
+<!-- Seasonal decoration overlay — rendered above page content, below nav -->
+{#if siteDecoration}
+	<SeasonalDecoration mode={siteDecoration} />
+{/if}
+
+<style>
+/* Logo animation keyframes are defined globally in app.css */
+/* This block intentionally left minimal — all logo-anim-* classes live in app.css */
+</style>
diff --git a/ui/src/routes/admin/+layout.svelte b/ui/src/routes/admin/+layout.svelte
index e651e4e..0577f62 100644
--- a/ui/src/routes/admin/+layout.svelte
+++ b/ui/src/routes/admin/+layout.svelte
@@ -52,6 +52,11 @@
 			href: '/admin/changelog',
 			label: () => m.admin_nav_changelog(),
 			icon: `<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" /><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M7 4h10a2 2 0 012 2v12a2 2 0 01-2 2H7a2 2 0 01-2-2V6a2 2 0 012-2z" />`
+		},
+		{
+			href: '/admin/site-theme',
+			label: () => 'Site Theme',
+			icon: `<path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M7 21a4 4 0 01-4-4V5a2 2 0 012-2h4a2 2 0 012 2v12a4 4 0 01-4 4zm0 0h12a2 2 0 002-2v-4a2 2 0 00-2-2h-2.343M11 7.343l1.657-1.657a2 2 0 012.828 0l2.829 2.829a2 2 0 010 2.828l-8.486 8.485M7 17h.01" />`
 		}
 	];
 
diff --git a/ui/src/routes/admin/site-theme/+page.server.ts b/ui/src/routes/admin/site-theme/+page.server.ts
new file mode 100644
index 0000000..1dae934
--- /dev/null
+++ b/ui/src/routes/admin/site-theme/+page.server.ts
@@ -0,0 +1,7 @@
+import type { PageServerLoad } from './$types';
+import { getSiteConfig } from '$lib/server/pocketbase';
+
+export const load: PageServerLoad = async () => {
+	const config = await getSiteConfig();
+	return { config };
+};
diff --git a/ui/src/routes/admin/site-theme/+page.svelte b/ui/src/routes/admin/site-theme/+page.svelte
new file mode 100644
index 0000000..b1262bd
--- /dev/null
+++ b/ui/src/routes/admin/site-theme/+page.svelte
@@ -0,0 +1,160 @@
+<script lang="ts">
+	import type { PageData } from './$types';
+
+	let { data }: { data: PageData } = $props();
+
+	type Decoration = 'snow' | 'sakura' | 'fireflies' | 'leaves' | 'stars' | null;
+	type LogoAnimation = 'none' | 'glow' | 'rainbow' | 'pulse' | 'shimmer';
+
+	let decoration   = $state<Decoration>(data.config.decoration);
+	let logoAnimation = $state<LogoAnimation>(data.config.logoAnimation);
+	let eventLabel   = $state(data.config.eventLabel ?? '');
+
+	let saving = $state(false);
+	let saved  = $state(false);
+	let errMsg = $state('');
+
+	const DECORATIONS: { id: Decoration; label: string; emoji: string; desc: string }[] = [
+		{ id: null,         label: 'Off',        emoji: '✕',   desc: 'No decoration' },
+		{ id: 'snow',       label: 'Snow',        emoji: '❄️',  desc: 'Falling snowflakes — winter' },
+		{ id: 'sakura',     label: 'Sakura',      emoji: '🌸',  desc: 'Cherry blossom petals — spring' },
+		{ id: 'fireflies',  label: 'Fireflies',   emoji: '✨',  desc: 'Glowing fireflies — summer' },
+		{ id: 'leaves',     label: 'Leaves',      emoji: '🍂',  desc: 'Falling autumn leaves — fall' },
+		{ id: 'stars',      label: 'Stars',       emoji: '⭐',  desc: 'Twinkling stars — events / fantasy' },
+	];
+
+	const LOGO_ANIMATIONS: { id: LogoAnimation; label: string; desc: string }[] = [
+		{ id: 'none',     label: 'None',     desc: 'Default brand colour, no animation' },
+		{ id: 'glow',     label: 'Glow',     desc: 'Soft pulsing amber glow' },
+		{ id: 'shimmer',  label: 'Shimmer',  desc: 'Left-to-right shine sweep' },
+		{ id: 'pulse',    label: 'Pulse',    desc: 'Subtle scale pulse' },
+		{ id: 'rainbow',  label: 'Rainbow',  desc: 'Slow hue-rotate colour cycle' },
+	];
+
+	async function save() {
+		saving = true; saved = false; errMsg = '';
+		try {
+			const res = await fetch('/api/site-config', {
+				method: 'PUT',
+				headers: { 'Content-Type': 'application/json' },
+				body: JSON.stringify({ decoration, logoAnimation, eventLabel }),
+			});
+			if (!res.ok) {
+				const d = await res.json().catch(() => ({}));
+				errMsg = d.message ?? `Error ${res.status}`;
+			} else {
+				saved = true;
+				setTimeout(() => { saved = false; }, 3000);
+			}
+		} catch (e) {
+			errMsg = String(e);
+		} finally {
+			saving = false;
+		}
+	}
+</script>
+
+<svelte:head>
+	<title>Site Theme — Admin</title>
+</svelte:head>
+
+<div class="max-w-2xl">
+	<div class="mb-8">
+		<h1 class="text-2xl font-bold text-(--color-text) mb-1">Site Theme</h1>
+		<p class="text-sm text-(--color-muted)">
+			Control seasonal decorations and the nav logo animation globally.
+			Changes take effect for all users within ~60 seconds (server cache TTL).
+		</p>
+	</div>
+
+	<!-- ── Decoration ────────────────────────────────────────────────────── -->
+	<section class="mb-8">
+		<h2 class="text-sm font-semibold text-(--color-text) uppercase tracking-widest mb-3">Particle Decoration</h2>
+		<div class="grid grid-cols-2 sm:grid-cols-3 gap-2">
+			{#each DECORATIONS as d}
+				<button
+					type="button"
+					onclick={() => { decoration = d.id; }}
+					class="flex items-start gap-3 p-3 rounded-lg border text-left transition-all
+						{decoration === d.id
+							? 'border-(--color-brand) bg-(--color-surface-2) text-(--color-text)'
+							: 'border-(--color-border) bg-(--color-surface-2)/40 text-(--color-muted) hover:border-(--color-brand)/40 hover:text-(--color-text)'}"
+				>
+					<span class="text-xl leading-none shrink-0 mt-0.5">{d.emoji}</span>
+					<div class="min-w-0">
+						<p class="text-sm font-semibold leading-snug">{d.label}</p>
+						<p class="text-xs opacity-70 leading-snug mt-0.5">{d.desc}</p>
+					</div>
+				</button>
+			{/each}
+		</div>
+	</section>
+
+	<!-- ── Logo Animation ────────────────────────────────────────────────── -->
+	<section class="mb-8">
+		<h2 class="text-sm font-semibold text-(--color-text) uppercase tracking-widest mb-3">Logo Animation</h2>
+		<div class="flex flex-col gap-2">
+			{#each LOGO_ANIMATIONS as a}
+				<button
+					type="button"
+					onclick={() => { logoAnimation = a.id; }}
+					class="flex items-center gap-4 p-3 rounded-lg border text-left transition-all
+						{logoAnimation === a.id
+							? 'border-(--color-brand) bg-(--color-surface-2) text-(--color-text)'
+							: 'border-(--color-border) bg-(--color-surface-2)/40 text-(--color-muted) hover:border-(--color-brand)/40 hover:text-(--color-text)'}"
+				>
+					<!-- Preview of the logo text with the animation class applied -->
+					<span class="font-bold text-lg tracking-tight w-24 shrink-0 text-(--color-brand)
+						{a.id === 'glow'    ? 'logo-anim-glow'    : ''}
+						{a.id === 'shimmer' ? 'logo-anim-shimmer' : ''}
+						{a.id === 'pulse'   ? 'logo-anim-pulse'   : ''}
+						{a.id === 'rainbow' ? 'logo-anim-rainbow' : ''}
+					">libnovel</span>
+					<div>
+						<p class="text-sm font-semibold">{a.label}</p>
+						<p class="text-xs opacity-70">{a.desc}</p>
+					</div>
+					{#if logoAnimation === a.id}
+						<svg class="w-4 h-4 ml-auto shrink-0 text-(--color-brand)" fill="currentColor" viewBox="0 0 24 24">
+							<path d="M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z"/>
+						</svg>
+					{/if}
+				</button>
+			{/each}
+		</div>
+	</section>
+
+	<!-- ── Event Label ───────────────────────────────────────────────────── -->
+	<section class="mb-8">
+		<h2 class="text-sm font-semibold text-(--color-text) uppercase tracking-widest mb-1">Event Label <span class="normal-case font-normal text-(--color-muted)">(optional)</span></h2>
+		<p class="text-xs text-(--color-muted) mb-3">Short text shown as a small badge next to the logo, e.g. "Winter 2025" or "Sakura Festival". Leave blank to hide.</p>
+		<input
+			type="text"
+			maxlength="64"
+			placeholder="e.g. Winter 2025"
+			bind:value={eventLabel}
+			class="w-full px-3 py-2 rounded-lg bg-(--color-surface-2) border border-(--color-border) text-(--color-text) text-sm placeholder:text-(--color-muted) focus:outline-none focus:border-(--color-brand)/60"
+		/>
+	</section>
+
+	<!-- ── Save ──────────────────────────────────────────────────────────── -->
+	<div class="flex items-center gap-3">
+		<button
+			type="button"
+			onclick={save}
+			disabled={saving}
+			class="px-5 py-2 rounded-lg bg-(--color-brand) text-(--color-surface) font-semibold text-sm hover:bg-(--color-brand-dim) disabled:opacity-50 transition-colors"
+		>
+			{saving ? 'Saving…' : 'Save Changes'}
+		</button>
+		{#if saved}
+			<span class="text-sm text-green-400 flex items-center gap-1.5">
+				<svg class="w-4 h-4" fill="currentColor" viewBox="0 0 24 24"><path d="M9 16.17L4.83 12l-1.42 1.41L9 19 21 7l-1.41-1.41z"/></svg>
+				Saved
+			</span>
+		{/if}
+		{#if errMsg}
+			<span class="text-sm text-red-400">{errMsg}</span>
+		{/if}
+	</div>
+</div>
diff --git a/ui/src/routes/api/site-config/+server.ts b/ui/src/routes/api/site-config/+server.ts
new file mode 100644
index 0000000..9b9d279
--- /dev/null
+++ b/ui/src/routes/api/site-config/+server.ts
@@ -0,0 +1,57 @@
+import { json, error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { getSiteConfig, saveSiteConfig } from '$lib/server/pocketbase';
+import { log } from '$lib/server/logger';
+
+/**
+ * GET /api/site-config
+ * Public — returns current site-wide decoration/animation settings.
+ */
+export const GET: RequestHandler = async () => {
+	try {
+		const config = await getSiteConfig();
+		return json(config);
+	} catch (e) {
+		log.error('site-config', 'GET failed', { err: String(e) });
+		error(500, 'Failed to load site config');
+	}
+};
+
+/**
+ * PUT /api/site-config
+ * Admin only — updates decoration + logoAnimation + eventLabel.
+ */
+export const PUT: RequestHandler = async ({ request, locals }) => {
+	if (!locals.user || locals.user.role !== 'admin') {
+		error(403, 'Forbidden');
+	}
+
+	const body = await request.json().catch(() => null);
+	if (!body) error(400, 'Invalid JSON body');
+
+	const validDecorations = ['snow', 'sakura', 'fireflies', 'leaves', 'stars', null];
+	if (body.decoration !== undefined && !validDecorations.includes(body.decoration)) {
+		error(400, `Invalid decoration — must be one of: ${validDecorations.filter(Boolean).join(', ')}, or null`);
+	}
+
+	const validLogoAnimations = ['none', 'glow', 'rainbow', 'pulse', 'shimmer'];
+	if (body.logoAnimation !== undefined && !validLogoAnimations.includes(body.logoAnimation)) {
+		error(400, `Invalid logoAnimation — must be one of: ${validLogoAnimations.join(', ')}`);
+	}
+
+	if (body.eventLabel !== undefined && typeof body.eventLabel !== 'string') {
+		error(400, 'eventLabel must be a string');
+	}
+
+	try {
+		await saveSiteConfig({
+			decoration: body.decoration ?? null,
+			logoAnimation: body.logoAnimation ?? 'none',
+			eventLabel: typeof body.eventLabel === 'string' ? body.eventLabel.slice(0, 64) : '',
+		});
+		return json({ ok: true });
+	} catch (e) {
+		log.error('site-config', 'PUT failed', { err: String(e) });
+		error(500, 'Failed to save site config');
+	}
+};