Changing text background color on HTML web pages

[ittiandro]

I have downloaded a library collection to the extSD card of my Android tablet ( Samsung Galaxy 4).
The books open in Chrome ( or Firefox) as HTML files, with the text pages on a standard white background, which is a bit hard on my eyes, especially at night.
Is it possible to change the background color of the pages?( not the web page, but the document displayed, i.e the book pages) How? Which software?
I know there are HTML editors, but they involve some programming and are a bit beyond me. Besides, I don’t think that they are the right tool for what I want to do.

Any suggestions?

Thanks

Ittiandro

 

[ittiandro]

I'll try to heed the private e-mail request to clarify my question, although I fail to understand what is not clear.

Basically, I'd like to change the white background color of documents opened in the browser (Chrome or Firefox).
The document( s) are the pages of books belonging to a collection. These book pages are html files accessible through the browser r with the path " file:///C:/Users/username/Documents/name of folder/subfolder.
The subfolder contains the index( list) of books. By clicking on the name of the book, a book folder opens containing the list of book's pages as " pb_book number .page.xml.html.
By clicking on the first " pb_......xml'html " file, the book opens on a white background. This is what I'd like to change, but I am unable. By right-clicking on different parts of the page, I get to an " Inspect source" option. Then an editing page opens where I can change the background color and the font color of the selected part of the page. Unfortunately the background of the text page remains white.
This is what I'd like to change because it is a bit harder for my eyes to read on such a bright white, especially at night..( I am 74)

I hope this is clearer now.

Thanks

Ittiandro