diff --git a/app/contributors/ContributorsSearch.responsive-breakpoints.test.tsx b/app/contributors/ContributorsSearch.responsive-breakpoints.test.tsx
new file mode 100644
index 000000000..7a17b2b30
--- /dev/null
+++ b/app/contributors/ContributorsSearch.responsive-breakpoints.test.tsx
@@ -0,0 +1,133 @@
+import { describe, it, expect, vi } from 'vitest';
+import React, { type ReactNode } from 'react';
+import { render, screen, fireEvent } from '@testing-library/react';
+import '@testing-library/jest-dom/vitest';
+import ContributorsSearch from './ContributorsSearch';
+
+vi.mock('next/link', () => ({
+  default: ({ children, href }: { children: ReactNode; href: string }) => (
+    <a href={href}>{children}</a>
+  ),
+}));
+
+vi.mock('next/image', () => ({
+  default: ({
+    src,
+    alt,
+    width,
+    height,
+  }: {
+    src: string;
+    alt: string;
+    width: number;
+    height: number;
+  }) => (
+    // eslint-disable-next-line @next/next/no-img-element
+    <img src={src} alt={alt} width={width} height={height} />
+  ),
+}));
+
+vi.mock('framer-motion', () => ({
+  motion: new Proxy(
+    {},
+    {
+      get:
+        (_, tag) =>
+        ({ children, ...props }: { children?: ReactNode; [key: string]: unknown }) =>
+          React.createElement(tag as string, props, children),
+    }
+  ),
+  AnimatePresence: ({ children }: { children?: ReactNode }) => <>{children}</>,
+}));
+
+vi.mock('lucide-react', () => ({
+  Search: () => <svg data-testid="search-icon" />,
+  GitFork: () => <svg data-testid="gitfork-icon" />,
+  X: () => <svg data-testid="close-icon" />,
+}));
+
+const mockContributors = [
+  {
+    id: 1,
+    login: 'alice',
+    avatar_url: 'https://example.com/alice.png',
+    contributions: 42,
+    html_url: 'https://github.com/alice',
+  },
+  {
+    id: 2,
+    login: 'bob',
+    avatar_url: 'https://example.com/bob.png',
+    contributions: 17,
+    html_url: 'https://github.com/bob',
+  },
+];
+
+describe('ContributorsSearch Responsive Breakpoints & Mobile Viewports', () => {
+  it('1. Mocks standard mobile-width media coordinates and renders without crashing', () => {
+    const originalWidth = window.innerWidth;
+    Object.defineProperty(window, 'innerWidth', { writable: true, configurable: true, value: 375 });
+    window.dispatchEvent(new Event('resize'));
+
+    render(<ContributorsSearch contributors={mockContributors} />);
+    expect(screen.getByText('alice')).toBeInTheDocument();
+    expect(screen.getByText('bob')).toBeInTheDocument();
+
+    Object.defineProperty(window, 'innerWidth', {
+      writable: true,
+      configurable: true,
+      value: originalWidth,
+    });
+  });
+
+  it('2. Asserts that columns reflow into standard single-column grids on mobile', () => {
+    const { container } = render(<ContributorsSearch contributors={mockContributors} />);
+    const gridContainer = container.querySelector('.grid');
+
+    expect(gridContainer).toBeInTheDocument();
+    expect(gridContainer).toHaveClass('grid-cols-1');
+    expect(gridContainer).toHaveClass('sm:grid-cols-2');
+    expect(gridContainer).toHaveClass('lg:grid-cols-3');
+    expect(gridContainer).toHaveClass('xl:grid-cols-4');
+  });
+
+  it('3. Verifies that styling values are not absolute widths that cause horizontal scrollbars', () => {
+    const { container } = render(<ContributorsSearch contributors={mockContributors} />);
+    const elementsWithClass = container.querySelectorAll('[class]');
+
+    elementsWithClass.forEach((el) => {
+      const className = el.getAttribute('class') || '';
+      expect(className).not.toMatch(/\bw-\[\d+px\]/);
+    });
+  });
+
+  it('4. Checks that navigation & input elements scale down gracefully using relative widths', () => {
+    const { container } = render(<ContributorsSearch contributors={mockContributors} />);
+
+    const searchContainer = container.querySelector('#contributors');
+    expect(searchContainer).toBeInTheDocument();
+    expect(searchContainer).toHaveClass('max-w-xl');
+    expect(searchContainer).toHaveClass('mx-auto');
+
+    const searchInput = screen.getByPlaceholderText(/Search the collective.../i);
+    expect(searchInput).toHaveClass('w-full');
+  });
+
+  it('5. Asserts mobile-friendly search toggle and clear state responds cleanly', () => {
+    render(<ContributorsSearch contributors={mockContributors} />);
+
+    expect(screen.queryByLabelText(/Clear search/i)).toBeNull();
+
+    const searchInput = screen.getByPlaceholderText(
+      /Search the collective.../i
+    ) as HTMLInputElement;
+    fireEvent.change(searchInput, { target: { value: 'alice' } });
+
+    const clearButton = screen.getByLabelText(/Clear search/i);
+    expect(clearButton).toBeInTheDocument();
+
+    fireEvent.click(clearButton);
+    expect(searchInput.value).toBe('');
+    expect(screen.queryByLabelText(/Clear search/i)).toBeNull();
+  });
+});