Flashing content does not exceed the general flash threshold (i.e., no
flashes with an intensity greater than 3 Hz and less than 55 Hz).
This test case has flashing lights
Div exceeds Hz threshold:
This flashing div has an intensity of 4hz thus exceeding the general
flash threshold:
Note: Hard to automatically test/detect. A human tester or AI is required
to (visually) verify if the flashing content frequency is between
approximately 4 Hz and 55 Hz.