there is no
display: Nightmode (or similar0
e-book standard
You would think that after all these years, that we would actually have meaningful (to users) standards. EPUB3 fell out of the 500lb Gorilla tree
RIAA created a standard for the recording industry (up till then, every lable had its own compensation curve)
The video (TV/Movie) industry has standards
Even the power company has (country specific) standards for Voltage, Frequency and power plugs
Not e-books