2.3.1 Three Flashes or Below Threshold
User interface components and navigation must be operable.
Do not design content in a way that is known to cause seizures or physical reactions.
Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds.
Note 1: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.