diff --git a/packages/ui/src/__mocks__/logto.tsx b/packages/ui/src/__mocks__/logto.tsx
index 885e34394..5aba77c0c 100644
--- a/packages/ui/src/__mocks__/logto.tsx
+++ b/packages/ui/src/__mocks__/logto.tsx
@@ -288,3 +288,17 @@ export const mockSignInMethodSettingsTestCases: Array<SignIn['methods']> = [
     },
   ],
 ];
+
+export const getBoundingClientRectMock = (mock: Partial<DOMRect>) =>
+  jest.fn(() => ({
+    width: 0,
+    height: 0,
+    x: 0,
+    y: 0,
+    top: 0,
+    bottom: 0,
+    left: 0,
+    right: 0,
+    ...mock,
+    toJSON: jest.fn(),
+  }));
diff --git a/packages/ui/src/components/InputFields/SmartInputField/AnimatedPrefix/index.tsx b/packages/ui/src/components/InputFields/SmartInputField/AnimatedPrefix/index.tsx
index 3472efe11..b66bff101 100644
--- a/packages/ui/src/components/InputFields/SmartInputField/AnimatedPrefix/index.tsx
+++ b/packages/ui/src/components/InputFields/SmartInputField/AnimatedPrefix/index.tsx
@@ -1,7 +1,7 @@
 import { onResize, useIsomorphicLayoutEffect } from '@react-spring/shared';
 import { useSpring, animated, config } from '@react-spring/web';
 import type { Nullable } from '@silverhand/essentials';
-import { cloneElement, useCallback, useRef } from 'react';
+import { cloneElement, useCallback, useRef, useState } from 'react';
 
 import * as styles from './index.module.scss';
 
@@ -11,6 +11,7 @@ type Props = {
 };
 
 const AnimatedPrefix = ({ children, isVisible }: Props) => {
+  const [domReady, setDomReady] = useState(false);
   const elementRef = useRef<Nullable<HTMLElement>>(null);
 
   // Get target width for the children
@@ -21,11 +22,14 @@ const AnimatedPrefix = ({ children, isVisible }: Props) => {
 
   const [animation, api] = useSpring(
     () => ({ width: getTargetWidth(), config: { ...config.default, clamp: true } }),
-    [getTargetWidth]
+    [getTargetWidth, domReady]
   );
 
   useIsomorphicLayoutEffect(() => {
     const { current } = elementRef;
+
+    setDomReady(true);
+
     const cleanup =
       current &&
       onResize(
diff --git a/packages/ui/src/components/InputFields/SmartInputField/index.test.tsx b/packages/ui/src/components/InputFields/SmartInputField/index.test.tsx
index dfb76a650..5456c5551 100644
--- a/packages/ui/src/components/InputFields/SmartInputField/index.test.tsx
+++ b/packages/ui/src/components/InputFields/SmartInputField/index.test.tsx
@@ -3,6 +3,7 @@ import { Globals } from '@react-spring/web';
 import { assert } from '@silverhand/essentials';
 import { fireEvent, render } from '@testing-library/react';
 
+import { getBoundingClientRectMock } from '@/__mocks__/logto';
 import { getDefaultCountryCallingCode } from '@/utils/country-code';
 
 import type { IdentifierInputType } from '.';
@@ -15,6 +16,7 @@ jest.mock('i18next', () => ({
 
 describe('SmartInputField Component', () => {
   const onChange = jest.fn();
+
   const defaultCountryCallingCode = getDefaultCountryCallingCode();
 
   const renderInputField = (props: {
@@ -27,6 +29,11 @@ describe('SmartInputField Component', () => {
     Globals.assign({
       skipAnimation: true,
     });
+
+    // eslint-disable-next-line @silverhand/fp/no-mutation
+    window.HTMLDivElement.prototype.getBoundingClientRect = getBoundingClientRectMock({
+      width: 100,
+    });
   });
 
   afterEach(() => {
@@ -65,10 +72,7 @@ describe('SmartInputField Component', () => {
       const countryCode = queryAllByText(`+${defaultCountryCallingCode}`);
       expect(countryCode).toHaveLength(2);
 
-      // Country code select should have a >0 width.
-      // The React Spring acquires the child element's width ahead of elementRef is properly set.
-      // So the value returns null. Assert style is null to represent the width is >0.
-      expect(queryByTestId('prefix')?.getAttribute('style')).toBe(null);
+      expect(queryByTestId('prefix')?.style.width).toBe('100px');
 
       const selector = container.querySelector('select');
       assert(selector, new Error('selector should not be null'));
diff --git a/packages/ui/src/pages/ForgotPassword/index.test.tsx b/packages/ui/src/pages/ForgotPassword/index.test.tsx
index c0612a6a1..feeb9715f 100644
--- a/packages/ui/src/pages/ForgotPassword/index.test.tsx
+++ b/packages/ui/src/pages/ForgotPassword/index.test.tsx
@@ -5,7 +5,7 @@ import { MemoryRouter, useLocation } from 'react-router-dom';
 
 import renderWithPageContext from '@/__mocks__/RenderWithPageContext';
 import SettingsProvider from '@/__mocks__/RenderWithPageContext/SettingsProvider';
-import { mockSignInExperienceSettings } from '@/__mocks__/logto';
+import { mockSignInExperienceSettings, getBoundingClientRectMock } from '@/__mocks__/logto';
 import type { SignInExperienceResponse } from '@/types';
 
 import ForgotPassword from '.';
@@ -43,6 +43,11 @@ describe('ForgotPassword', () => {
     Globals.assign({
       skipAnimation: true,
     });
+
+    // eslint-disable-next-line @silverhand/fp/no-mutation
+    window.HTMLDivElement.prototype.getBoundingClientRect = getBoundingClientRectMock({
+      width: 100,
+    });
   });
 
   afterEach(() => {
@@ -79,6 +84,7 @@ describe('ForgotPassword', () => {
       const { queryByText, queryAllByText, container, queryByTestId } = renderPage(settings);
       const inputField = container.querySelector('input[name="identifier"]');
       const countryCodeSelectorPrefix = queryByTestId('prefix');
+
       assert(inputField, new Error('input field not found'));
 
       expect(queryByText('description.reset_password')).not.toBeNull();
@@ -88,12 +94,7 @@ describe('ForgotPassword', () => {
 
       if (state.identifier === SignInIdentifier.Phone && settings.phone) {
         expect(inputField.getAttribute('value')).toBe(phone);
-
-        // Country code select should have a >0 width.
-        // The React Spring acquires the child element's width ahead of elementRef is properly set.
-        // So the value returns null. Assert style is null to represent the width is >0.
-        expect(countryCodeSelectorPrefix?.getAttribute('style')).toBeNull();
-
+        expect(countryCodeSelectorPrefix?.style.width).toBe('100px');
         expect(queryAllByText(`+${countryCode}`)).toHaveLength(2);
       } else if (state.identifier === SignInIdentifier.Phone) {
         // Phone Number not enabled
@@ -107,7 +108,7 @@ describe('ForgotPassword', () => {
       } else if (state.identifier === SignInIdentifier.Email) {
         // Only PhoneNumber is enabled
         expect(inputField.getAttribute('value')).toBe('');
-        expect(countryCodeSelectorPrefix?.getAttribute('style')).toBeNull();
+        expect(countryCodeSelectorPrefix?.style.width).toBe('100px');
       }
 
       if (state.identifier === SignInIdentifier.Username && settings.email) {
@@ -116,7 +117,7 @@ describe('ForgotPassword', () => {
       } else if (state.identifier === SignInIdentifier.Username) {
         // Only PhoneNumber is enabled
         expect(inputField.getAttribute('value')).toBe('');
-        expect(countryCodeSelectorPrefix?.getAttribute('style')).toBeNull();
+        expect(countryCodeSelectorPrefix?.style.width).toBe('100px');
       }
     });
   });