You can change the background color of your PDFs by setting the Themes according to your needs in the different reading environments to reduce eye strain.
1. To select the theme, you can enter reading page -> Page Display -> Themes. It enables you to choose from the four default modes, or customize any color in your own preference;
2. You can also right-click anywhere in the PDF and choose Themes from the pop-up menu.
Light Mode: The default one that displays the document on a bright white background.
Sepia Mode: Displays the document in a light-yellow background, so it’s easier on your eyes.
Dark Mode: Displays the document in inverse color (like it is on film negatives) in a dark environment.
Reseda Mode: Displays the document in a light-green background to protect your eyes after long-time reading.