Success Criterion 2.3.1
Conformance level A

Content Flashing Faster Than 3 Times per Second

2.3.1 — Three Flashes or Below Threshold

Scenario

Setting

An email client's compose window

What’s wrong

A loading animation flashes bright red and white more than three times per second while the compose window saves a draft, with no way to disable or reduce it.

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

Run the content through the Photosensitive Epilepsy Analysis Tool (PEAT): confirm no flash exceeds 3 times per second within any one-second window.

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 an email client's compose window, this barrier is gone for people with photosensitive epilepsy and others sensitive to rapid flashing — they reach the same outcome without extra effort.

Who is affected