A dark mode for Sumatra PDF is really easy – you just need to tinker with 3 lines of code in the settings.
Why Use Sumatra PDF?
In my opinion, it’s the best PDF reader. It’s small in size, super-fast and doesn’t have any annoying cruft.
Why a Dark Mode (Night Mode)?
If you code for long periods of time, then it’s really great to have your code editor run in dark mode. This greatly reduces the strain on the eyes.
But let’s say you are also following along an e-book, maybe a PDF and you switch to Sumatra PDF. The default setting is black text on white background. Immediately your eyes are shocked with bright luminescent white light. It’s as if you were relaxing in a room with the lights switched off and suddenly someone walked in and abruptly turned the lights on.
As you are coding along you have to switch back and forth multiple times between your PDF reader and code editor. It can be really jarring for the eyes and nerves.
How to Enable Dark Mode?
In Sumatra PDF, click on the Menu -> Settings -> Advanced Options
This should open the SumatraPDF-settings.txt file in your text editor. Change the following 3 lines under the heading FixedPageUI:
TextColor = #eeeeee
BackgroundColor = #111111
GradientColors = #000000
TextColor changes the text color of the PDF document. Background color changes, well the background color of the PDF document. GradientColors will change the background window of Sumatra PDF.