> p.s. Do you know how I would go about recommending someone add the ability to have green or amber text on the black background?

If you're on Android:

1. go to Settings -> Info -> About

2. Draw a lowercase h on the screen (anywhere), and you'll see a "special color mode enabled", and should get amber on black. another letter gives you green on black, but I forget which :( . There's a bunch of hidden color combinations there :)

I'm not sure that exists on iOS, though

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For requesting it: help & feedback -> contact us -> give feedback is your best bet. I'm out of touch w/ the Kindle team, but at least several years ago many of the devs would obsessively read customer feedback (that wasn't deemed sensitive/PII)