diff --git a/examples/chat/angular/src/app/shell/control-palette.component.html b/examples/chat/angular/src/app/shell/control-palette.component.html
index 521fb21f3..c8dbd0ef3 100644
--- a/examples/chat/angular/src/app/shell/control-palette.component.html
+++ b/examples/chat/angular/src/app/shell/control-palette.component.html
@@ -60,6 +60,15 @@
       </select>
     </label>
 
+    <label class="palette__group palette__group--model">
+      <span class="palette__label">Theme</span>
+      <select [value]="theme()" (change)="pickTheme($event)">
+        @for (opt of themeOptions(); track opt.value) {
+          <option [value]="opt.value" [selected]="opt.value === theme()">{{ opt.label }}</option>
+        }
+      </select>
+    </label>
+
     <button
       type="button"
       class="palette__toggle"
diff --git a/examples/chat/angular/src/app/shell/control-palette.component.ts b/examples/chat/angular/src/app/shell/control-palette.component.ts
index d456aca44..ffdc18382 100644
--- a/examples/chat/angular/src/app/shell/control-palette.component.ts
+++ b/examples/chat/angular/src/app/shell/control-palette.component.ts
@@ -28,12 +28,15 @@ export class ControlPalette {
   readonly effortOptions = input.required<readonly { value: string; label: string }[]>();
   readonly genUiMode = input.required<string>();
   readonly genUiOptions = input.required<readonly { value: string; label: string }[]>();
+  readonly theme = input.required<string>();
+  readonly themeOptions = input.required<readonly { value: string; label: string }[]>();
   readonly debugOpen = input.required<boolean>();
 
   readonly modeChange = output<DemoMode>();
   readonly modelChange = output<string>();
   readonly effortChange = output<string>();
   readonly genUiModeChange = output<string>();
+  readonly themeChange = output<string>();
   readonly debugOpenChange = output<boolean>();
   readonly newConversation = output<void>();
 
@@ -68,6 +71,11 @@ export class ControlPalette {
     this.genUiModeChange.emit(value);
   }
 
+  protected pickTheme(event: Event): void {
+    const value = (event.target as HTMLSelectElement).value;
+    this.themeChange.emit(value);
+  }
+
   protected toggleDebug(): void {
     this.debugOpenChange.emit(!this.debugOpen());
   }
diff --git a/examples/chat/angular/src/app/shell/demo-shell.component.html b/examples/chat/angular/src/app/shell/demo-shell.component.html
index 75fd9aad8..14ef6b0a5 100644
--- a/examples/chat/angular/src/app/shell/demo-shell.component.html
+++ b/examples/chat/angular/src/app/shell/demo-shell.component.html
@@ -9,11 +9,14 @@
     [effortOptions]="effortOptions()"
     [genUiMode]="genUiMode()"
     [genUiOptions]="genUiOptions()"
+    [theme]="theme()"
+    [themeOptions]="themeOptions()"
     [debugOpen]="debugOpen()"
     (modeChange)="onModeChange($event)"
     (modelChange)="onModelChange($event)"
     (effortChange)="onEffortChange($event)"
     (genUiModeChange)="onGenUiModeChange($event)"
+    (themeChange)="onThemeChange($event)"
     (debugOpenChange)="onDebugChange($event)"
     (newConversation)="onNewConversation()"
   />
diff --git a/examples/chat/angular/src/app/shell/demo-shell.component.ts b/examples/chat/angular/src/app/shell/demo-shell.component.ts
index 51e21049b..d5fcdd778 100644
--- a/examples/chat/angular/src/app/shell/demo-shell.component.ts
+++ b/examples/chat/angular/src/app/shell/demo-shell.component.ts
@@ -2,6 +2,8 @@
 import {
   Component,
   ChangeDetectionStrategy,
+  DOCUMENT,
+  effect,
   signal,
   inject,
 } from '@angular/core';
@@ -37,6 +39,16 @@ function modeFromUrl(url: string): DemoMode {
 export class DemoShell {
   private readonly router = inject(Router);
   private readonly persistence = inject(PalettePersistence);
+  private readonly document = inject(DOCUMENT);
+
+  constructor() {
+    // Reflect the chosen theme onto <html data-theme="..."> so the
+    // global stylesheet's scoped --a2ui-* overrides activate. Runs on
+    // signal change including initial mount (read from persistence).
+    effect(() => {
+      this.document.documentElement.setAttribute('data-theme', this.theme());
+    });
+  }
 
   protected readonly mode = toSignal(
     this.router.events.pipe(
@@ -64,6 +76,13 @@ export class DemoShell {
    */
   readonly genUiMode = signal<string>(this.persistence.read('genUiMode') ?? 'a2ui');
 
+  /**
+   * A2UI theme preset for the rendered surface. Toggles a `data-theme`
+   * attribute on the document root which the global stylesheet keys
+   * scoped `--a2ui-*` overrides off. Persisted across reloads.
+   */
+  readonly theme = signal<string>(this.persistence.read('theme') ?? 'default-dark');
+
   protected readonly debugOpen = signal<boolean>(this.persistence.read('debug') ?? false);
 
   protected readonly modelOptions = signal<readonly { value: string; label: string }[]>([
@@ -84,6 +103,13 @@ export class DemoShell {
     { value: 'json-render', label: 'json-render' },
   ]);
 
+  protected readonly themeOptions = signal<readonly { value: string; label: string }[]>([
+    { value: 'default-dark',   label: 'Default dark' },
+    { value: 'default-light',  label: 'Default light' },
+    { value: 'material-dark',  label: 'Material dark' },
+    { value: 'material-light', label: 'Material light' },
+  ]);
+
   /** Persisted thread id (null on first run). Reactive so reload reconnects to the same thread. */
   private readonly threadIdSignal = signal<string | null>(this.persistence.read('threadId') ?? null);
 
@@ -145,6 +171,11 @@ export class DemoShell {
     this.persistence.write('genUiMode', next);
   }
 
+  protected onThemeChange(next: string): void {
+    this.theme.set(next);
+    this.persistence.write('theme', next);
+  }
+
   protected onDebugChange(next: boolean): void {
     this.debugOpen.set(next);
     this.persistence.write('debug', next);
diff --git a/examples/chat/angular/src/app/shell/palette-persistence.service.ts b/examples/chat/angular/src/app/shell/palette-persistence.service.ts
index d0e0a3fc7..2742feb40 100644
--- a/examples/chat/angular/src/app/shell/palette-persistence.service.ts
+++ b/examples/chat/angular/src/app/shell/palette-persistence.service.ts
@@ -7,6 +7,7 @@ interface PaletteState {
   model?: string | null;
   effort?: string | null;
   genUiMode?: string | null;
+  theme?: string | null;
   debug?: boolean | null;
   threadId?: string | null;
   collapsed?: boolean | null;
diff --git a/examples/chat/angular/src/styles.css b/examples/chat/angular/src/styles.css
index 9555ba8fa..3c08dd26e 100644
--- a/examples/chat/angular/src/styles.css
+++ b/examples/chat/angular/src/styles.css
@@ -14,3 +14,73 @@ html, body {
   background: #0f1116;
   color: #e6e9ef;
 }
+
+/*
+ * A2UI theme presets — switched at runtime via the palette "Theme"
+ * dropdown by toggling `data-theme` on the document root. Mirrors the
+ * preset CSS files shipped from `@ngaf/chat/themes/*.css`; we inline
+ * them here to avoid the workspace-vs-published-path resolution
+ * complexity of importing them dynamically. Default ('default-dark')
+ * uses the lib's :host defaults, so no override block is needed.
+ */
+
+html[data-theme='default-light'] {
+  --a2ui-primary: #4f8df5;
+  --a2ui-on-primary: #ffffff;
+  --a2ui-primary-hover: #3b7be3;
+  --a2ui-secondary: #5b6275;
+  --a2ui-on-secondary: #ffffff;
+  --a2ui-surface: #fafafa;
+  --a2ui-on-surface: #1a1d23;
+  --a2ui-surface-variant: rgba(0, 0, 0, 0.04);
+  --a2ui-on-surface-variant: rgba(0, 0, 0, 0.6);
+  --a2ui-outline: rgba(0, 0, 0, 0.12);
+  --a2ui-outline-variant: rgba(0, 0, 0, 0.06);
+  --a2ui-error: #d33533;
+  --a2ui-on-error: #ffffff;
+  --a2ui-scrim: rgba(0, 0, 0, 0.4);
+  --a2ui-elevation-1: 0 1px 2px rgba(0, 0, 0, 0.08);
+  --a2ui-elevation-2: 0 2px 4px rgba(0, 0, 0, 0.10);
+  --a2ui-elevation-3: 0 4px 8px rgba(0, 0, 0, 0.12);
+  --a2ui-elevation-4: 0 8px 16px rgba(0, 0, 0, 0.14);
+  --a2ui-elevation-5: 0 16px 32px rgba(0, 0, 0, 0.16);
+}
+
+html[data-theme='material-dark'] {
+  --a2ui-primary: #D0BCFF;
+  --a2ui-on-primary: #381E72;
+  --a2ui-primary-hover: #B69DF8;
+  --a2ui-secondary: #CCC2DC;
+  --a2ui-on-secondary: #332D41;
+  --a2ui-surface: #1C1B1F;
+  --a2ui-on-surface: #E6E1E5;
+  --a2ui-surface-variant: #49454F;
+  --a2ui-on-surface-variant: #CAC4D0;
+  --a2ui-outline: #938F99;
+  --a2ui-outline-variant: #49454F;
+  --a2ui-error: #F2B8B5;
+  --a2ui-on-error: #601410;
+  --a2ui-scrim: rgba(0, 0, 0, 0.6);
+}
+
+html[data-theme='material-light'] {
+  --a2ui-primary: #6750A4;
+  --a2ui-on-primary: #FFFFFF;
+  --a2ui-primary-hover: #533F8E;
+  --a2ui-secondary: #625B71;
+  --a2ui-on-secondary: #FFFFFF;
+  --a2ui-surface: #FFFBFE;
+  --a2ui-on-surface: #1C1B1F;
+  --a2ui-surface-variant: #E7E0EC;
+  --a2ui-on-surface-variant: #49454F;
+  --a2ui-outline: #79747E;
+  --a2ui-outline-variant: #CAC4D0;
+  --a2ui-error: #B3261E;
+  --a2ui-on-error: #FFFFFF;
+  --a2ui-scrim: rgba(0, 0, 0, 0.4);
+  --a2ui-elevation-1: 0 1px 2px rgba(0, 0, 0, 0.08);
+  --a2ui-elevation-2: 0 2px 4px rgba(0, 0, 0, 0.10);
+  --a2ui-elevation-3: 0 4px 8px rgba(0, 0, 0, 0.12);
+  --a2ui-elevation-4: 0 8px 16px rgba(0, 0, 0, 0.14);
+  --a2ui-elevation-5: 0 16px 32px rgba(0, 0, 0, 0.16);
+}
