- 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
A QA pass on a government tax-filing portal turns this up: media queries stopping at 768px so mobile breakpoint never engages under desktop zoom.
Why it matters
Low-vision users at high zoom and people reading on narrow mobile viewports. On a government tax-filing portal, that means they can't perceive the control's boundary or state.
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.
Outcome
With the fix in place on a government tax-filing portal, they tell the information apart without relying on color.
Who is affected
Low-vision users at high zoom and people reading on narrow mobile viewports.
Learn more
- Understanding Understanding document (opens in a new tab)
Related scenarios
- Content or Controls That Vanish Entirely When the Page Reflows
- Vertical Content That Forces Horizontal Scrolling at 320px
- Fixed-Width Container Forcing Scrolling in Two Directions
- Overlapping Content When the Page Is Zoomed to 400%
- Sticky Bars That Eat Up Most of a 320px Mobile Screen
- Long Unbroken Text or URL That Forces Horizontal Scrolling