Re Kindle Night Mode CSS:
Funny, Aaron Troia
asked the same thing here: if it's possible to target night mode with a media query or somesuch. After review, I don't think it's possible.
In iBooks, Apple changes between Night/Sepia/Etc. by attaching a CSS class to the root document element. So you can actually detect when it changes and so on and adjust for it in your own CSS--which is awesome, until people get around to adopting the legitimate night-mode media query. (Although, what about sepia/half-night mode/any others? Something for the CSS standards body to think about...)