I do agree with you, Sophronia. The yellow color in the background makes my eyes more healthy and less tired if I'm reading huge amounts of texts. For the PDF format, I'm using the app you mentioned, PDF expert. For the fb2 formats, I prefer the FB reader application. When I read the normal books, I use the proper lens for reading with a yellow filter to keep my eyes in a good state, because due to my work purposes, I read for 10-8 hrs per day, so this is very important to use the proper lens. Usually, I buy a lens at the https://www.cosplaylens.com site at an affordable price.
I do agree with you, Sophronia. The yellow color in the background makes my eyes more healthy and less tired if I'm reading huge amounts of texts. For the PDF format, I'm using the app you mentioned, PDF expert. For the fb2 formats, I prefer the FB reader application. When I read the normal books, I use the proper lens for reading with a yellow filter to keep my eyes in a good state, because due to my work purposes, I read for 10-8 hrs per day, so this is very important to use the proper lens. Usually, I buy a lens at the https://www.cosplaylens.com site at an affordable price.