I would like all text on webpages to be clear black and white, legally blind

I am legally blind and can set up my other software to be more visually accessible. However, with any of the internet browsers, a lot of text and messages include portions that are pale blue or some other pale color that is very difficult (even with magnification) to read. Is it possible to set my Firefox browser to print text in black and white at all times? Thank you for any suggestions, Kay