How to Test Mobile Responsiveness in Vibecoded Apps

Use browser DevTools to test your app at common breakpoints: 320px (small phones), 375px (iPhone), 414px (larger phones), 768px (tablets), and 1024px (small laptops). Slowly drag the viewport width and watch for layout jumps or elements that overlap, overflow, or disappear at certain widths.

Pay close attention to the transitions between breakpoints. AI-generated CSS often handles specific sizes well but breaks at the in-between widths. Check that navigation menus collapse properly, images scale without distortion, and text remains readable without horizontal scrolling at every width.

Mobile users tap, swipe, and pinch — they do not hover. Test that all hover-dependent interactions have touch equivalents. Dropdown menus that open on hover are a classic vibecoded bug on mobile. Buttons and links should have adequate tap targets (at least 44x44 pixels) with enough spacing to prevent accidental taps on adjacent elements.

Test gestures if your app uses them: swipe to delete, pull to refresh, or pinch to zoom. Verify that these gestures do not conflict with the browser's native gestures. Also check that modals and overlays are dismissible on mobile — AI-generated modals often lack a close button or have one that is off-screen on small devices.

Mobile devices have less processing power and often slower connections. Use Chrome DevTools to throttle CPU and network speed, then test page load times and interaction responsiveness. AI-generated apps frequently load large, unoptimized images and heavy JavaScript bundles that cripple mobile performance.

Test with the device orientation changing between portrait and landscape. The layout should adapt smoothly without losing user state or scroll position. Also verify that forms work properly with on-screen keyboards — the keyboard should not cover the active input field, and the page should scroll to keep the focused field visible.