1.4.10: Reflow

What it means

Content must reflow without two-dimensional scrolling when viewed at 320 CSS pixels wide and zoomed to 400%. Vertical scrolling is fine; users should not need to scroll sideways to read a sentence.

This matches typical phone widths at high zoom.

How to fix it

• Use flexible layouts instead of fixed pixel widths for main content.
• Avoid horizontal scroll caused by wide tables — offer reflow or an alternative view.
• Test at 320px width with 400% zoom in the browser.
• Do not rely on pinch-zoom alone to make desktop layouts usable on small screens.

Quick examples

• Good: A data table switches to stacked rows on narrow screens without sideways scroll.
• Bad: At 320px width the page keeps a 1200px layout and requires horizontal scrolling.
• Good: Form fields stack vertically and labels stay visible at high zoom.
• Bad: Fixed side-by-side columns clip labels when the viewport is narrow.