Flashing content (A)

Silktide asks you to confirm that nothing on your pages flashes more than three times per second. Rapid flashing can trigger seizures in people with photosensitive epilepsy, so this is checked through a human review of each page.

Why this matters

For people with photosensitive epilepsy, content that flashes rapidly is not merely unpleasant - it can cause a seizure within seconds, before they can look away or close the tab. Video, animations, and scripted effects are the usual sources. Because the stakes are physical harm, this is a requirement of (success criterion 2.3.1), the most basic tier of the standard.

How to fix it

This check is a prompt to review each page:

Watch the page's videos, animations, and any scripted effects. Look for anything that flashes - rapid alternation between light and dark or strongly contrasting states.
Confirm nothing flashes more than three times in any one-second period. At Level A, faster flashing is still acceptable only if it stays below the general-flash and red-flash thresholds - in practice, if the flashing area is very small or the change in brightness is low. The Understanding document linked below defines the thresholds precisely.
Remove or slow down anything that fails - re-edit videos and reduce animation frequency in code.
Once you are satisfied the page is safe, the finding.

How Silktide tests this

Every page is flagged for manual review. Detecting flashing reliably requires observing the page's motion over time, including video content, which cannot be judged automatically.

Troubleshooting

This check covers WCAG 2.3.1 (Level A), which permits flashing below defined size and intensity thresholds. The stricter Flashing content (AAA) check covers success criterion 2.3.2, which permits no more than three flashes per second with no threshold exception. Meeting the AAA bar automatically satisfies this one.