diff --git a/app/customize/components/AdvancedSettingsPanel.theme-contrast.test.tsx b/app/customize/components/AdvancedSettingsPanel.theme-contrast.test.tsx
new file mode 100644
index 000000000..9413a867f
--- /dev/null
+++ b/app/customize/components/AdvancedSettingsPanel.theme-contrast.test.tsx
@@ -0,0 +1,105 @@
+import { render, screen } from '@testing-library/react';
+import '@testing-library/jest-dom/vitest';
+import { describe, it, expect, vi } from 'vitest';
+import { AdvancedSettingsPanel } from './AdvancedSettingsPanel';
+import type { ComponentProps } from 'react';
+import type { DeltaFormat, Language, Timezone, ViewMode } from '../types';
+
+vi.mock('./ThemeSelector', () => ({
+  StyledSelect: ({
+    children,
+    id,
+    value,
+    onChange,
+    ariaLabel,
+  }: {
+    children: React.ReactNode;
+    id?: string;
+    value?: string;
+    onChange?: (value: string) => void;
+    ariaLabel?: string;
+  }) => (
+    <select
+      id={id}
+      aria-label={ariaLabel}
+      value={value}
+      onChange={(e) => onChange?.(e.target.value)}
+    >
+      {children}
+    </select>
+  ),
+}));
+
+const defaultProps = {
+  hideTitle: false,
+  hideBackground: false,
+  hideStats: false,
+  viewMode: 'default' as ViewMode,
+  deltaFormat: 'percent' as DeltaFormat,
+  badgeWidth: '' as const,
+  badgeHeight: '' as const,
+  grace: 1,
+  language: 'en' as Language,
+  timezone: 'UTC' as Timezone,
+  onHideTitleChange: vi.fn(),
+  onHideBackgroundChange: vi.fn(),
+  onHideStatsChange: vi.fn(),
+  onViewModeChange: vi.fn(),
+  onDeltaFormatChange: vi.fn(),
+  onBadgeWidthChange: vi.fn(),
+  onBadgeHeightChange: vi.fn(),
+  onGraceChange: vi.fn(),
+  onLanguageChange: vi.fn(),
+  onTimezoneChange: vi.fn(),
+} satisfies ComponentProps<typeof AdvancedSettingsPanel>;
+
+describe('AdvancedSettingsPanel Theme Contrast', () => {
+  it('includes light and dark theme classes on section labels', () => {
+    const { container } = render(<AdvancedSettingsPanel {...defaultProps} />);
+
+    const labels = container.querySelectorAll('.text-gray-600.dark\\:text-white\\/60');
+
+    expect(labels.length).toBeGreaterThan(0);
+  });
+
+  it('includes light and dark theme classes on visibility controls', () => {
+    render(<AdvancedSettingsPanel {...defaultProps} />);
+
+    const checkboxLabel = screen.getByText('Hide Title');
+
+    expect(checkboxLabel.className).toContain('text-gray-700');
+    expect(checkboxLabel.className).toContain('dark:text-white/70');
+  });
+
+  it('includes light and dark theme classes on dimension inputs', () => {
+    render(<AdvancedSettingsPanel {...defaultProps} />);
+
+    const widthInput = screen.getByLabelText('Width');
+
+    expect(widthInput.className).toContain('bg-white/60');
+    expect(widthInput.className).toContain('dark:bg-black/40');
+    expect(widthInput.className).toContain('border-black/10');
+    expect(widthInput.className).toContain('dark:border-white/10');
+  });
+
+  it('includes theme-aware separator styling', () => {
+    const { container } = render(<AdvancedSettingsPanel {...defaultProps} />);
+
+    const separator = container.querySelector('.bg-black\\/5.dark\\:bg-white\\/5');
+
+    expect(separator).toBeTruthy();
+  });
+
+  it('includes theme-aware styling for grace controls', () => {
+    const { container } = render(<AdvancedSettingsPanel {...defaultProps} />);
+
+    const sliderTrack = container.querySelector('.bg-gray-300.dark\\:bg-white\\/6');
+
+    expect(sliderTrack).toBeTruthy();
+
+    const graceValue = screen.getByText(String(defaultProps.grace));
+
+    expect(graceValue.className).toContain('text-emerald-600');
+    expect(graceValue.className).toContain('dark:text-emerald-300/60');
+  });
+});