Success Criterion 1.4.10
Conformance level AA

Desktop Breakpoint That Never Switches to Mobile Layout

1.4.10 — Reflow

Scenario

Setting

A government tax-filing portal

What’s wrong

Media queries stopping at 768px so mobile breakpoint never engages under desktop zoom.

Example

.layout { width: 1200px; }

Why it matters

Low-vision users at high zoom and people reading on narrow mobile viewports.

How to test

Zoom a 1280px-wide desktop browser to 400%: if the mobile-style single-column layout never engages because breakpoints stop at 768px, it fails.

How to fix

At 320 CSS px width (400% zoom on a 1280px desktop), content must reflow into one column with only vertical scrolling and nothing missing or unreachable. .layout { max-width: 1200px; width: 100%; } Content must reflow into one column at 320px wide with no horizontal scrolling and nothing missing.

Outcome

On a government tax-filing portal, this barrier is gone for low-vision users at high zoom and people reading on narrow mobile viewports — they no longer have to work around this.

Who is affected