Only use this for 180 seconds.
When you open this page, the default 670nm color is displayed. If you select the gradient color option there is a subtle shift between red colors moving between 5 color steps.
You'll probably not notice the difference... but the base color is: 670nm (used in the study)
Then I add 4 super slight variations: 704nm, 705nm, 707nm, 709nm

If there is interest, I will add functionality:
the ability to select color stepping
HSL color profile
along with any good ideas...

Keyboard commands:
F for full screen, C for gradient, T for 3 minute timer.
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