There are problems with night mode when user has applied highlighters. Take a look at some portion of text in Normal mode, Night mode and what I propose.
This is how it looks now in Normal mode:
day_mode.png 564.48K 43 downloads
This is how Night Mode looks now:
night_mode.png 451.75K 69 downloads
As you can see, highlights makes impossible to read this text. Colors need to be adjusted for night mode.
My proposed look:
night_mode_new.png 549.56K 57 downloads
Highlighter color should be superimposed on the black background. Actually background could be a notch darker than it is now.