I find that line more distracting than scrolling.
I don't know what the solution might be, but this is not it.
I don't know what the solution might be, but this is not it.
I'm not sure if white or black gradient would be better though.
If you want to experiment the source code is at https://github.com/rdwallis/MagicScrollWebReader
The line is an impossible challenge to design because the break between pages should be very obvious but also not distracting to the reader.