diff --git a/frontend/src/lib/auth/SignupForm.svelte b/frontend/src/lib/auth/SignupForm.svelte
index 5637dd9..00c440b 100644
--- a/frontend/src/lib/auth/SignupForm.svelte
+++ b/frontend/src/lib/auth/SignupForm.svelte
@@ -139,7 +139,7 @@
 	<!-- Submit button -->
 	<button
 		type="submit"
-		class="w-full cursor-pointer rounded-[var(--radius-md)] bg-[var(--green)] px-[24px] py-[12px] text-[var(--btn-font-size)] font-[var(--btn-font-weight)] tracking-[var(--btn-letter-spacing)] text-white"
+		class="w-full cursor-pointer rounded-[var(--radius-md)] bg-[var(--green-dark)] px-[24px] py-[12px] text-[var(--btn-font-size)] font-[var(--btn-font-weight)] tracking-[var(--btn-letter-spacing)] text-white"
 	>
 		Konto erstellen &rarr;
 	</button>
diff --git a/frontend/src/lib/auth/SignupForm.test.ts b/frontend/src/lib/auth/SignupForm.test.ts
index e7fdddb..fc92dcf 100644
--- a/frontend/src/lib/auth/SignupForm.test.ts
+++ b/frontend/src/lib/auth/SignupForm.test.ts
@@ -116,6 +116,12 @@ describe('SignupForm', () => {
 		expect(screen.queryByText('Mindestens 8 Zeichen')).not.toBeInTheDocument();
 	});
 
+	it('submit button uses --green-dark for WCAG AA contrast', () => {
+		render(SignupForm);
+		const button = screen.getByRole('button', { name: /konto erstellen/i });
+		expect(button.className).toContain('bg-[var(--green-dark)]');
+	});
+
 	it('renders placeholders on inputs', () => {
 		render(SignupForm);
 		expect(screen.getByPlaceholderText('z.B. Sarah')).toBeInTheDocument();