I've only found that to be a problem with black text on white. I just finished an 800 page book on my phone with white text on black with no issues. I've found

I've only found that to be a problem with black text on white. I just finished an 800 page book on my phone with white text on black with no issues. I've found that I prefer reading on my phone to the kindle or physical book, mostly because the page turning is instant, my phone is always with me, and I can read one handed in bed without needing a light. If you have an android phone, check out Aldiko.