Why it matters
Flashing content can trigger seizures in people with photosensitive epilepsy. This is a safety-critical requirement — violations can cause real physical harm.
Common violations
- Rapidly flashing animations or GIFs
- Video content with strobe effects
- CSS animations with rapid color alternation
- Banner ads with fast blinking effects
Code examples
Bad
@keyframes flash {
0%, 100% { opacity: 1; }
25% { opacity: 0; }
50% { opacity: 1; }
75% { opacity: 0; }
}
.alert { animation: flash 0.5s infinite; }Good
@keyframes pulse {
0%, 100% { opacity: 1; }
50% { opacity: 0.7; }
}
.alert { animation: pulse 2s ease-in-out infinite; }
@media (prefers-reduced-motion: reduce) {
.alert { animation: none; }
}How to fix
Limit flashing to fewer than 3 times per second. Use smooth transitions instead of abrupt flashes. Respect prefers-reduced-motion. Test video content with photosensitive epilepsy analysis tools like PEAT.
Related criteria
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