Success Criterion 2.3.1
Conformance level A

Ad or User-Generated Content Never Screened for Flashing

2.3.1 — Three Flashes or Below Threshold

Scenario

Setting

A grocery delivery app's shopping cart

What’s wrong

Ad creatives/user-generated content embedded without flash screening.

Example

.alert-badge { animation: flash 0.2s infinite; } /* 5Hz */

Why it matters

People with photosensitive epilepsy and others sensitive to rapid flashing.

How to test

Review third-party ad creatives or user-generated content embedded on the page: unscreened content with flashing above threshold fails.

How to fix

Nothing may flash more than 3 times per second above the general or red-flash thresholds. .alert-badge { animation: flash 1s infinite; } /* below 3Hz threshold */ Content must not flash more than 3 times per second across a large enough area to matter.

Outcome

On a grocery delivery app's shopping cart, this barrier is gone for people with photosensitive epilepsy and others sensitive to rapid flashing — they can finish what they came here to do.

Who is affected