To modify the bottom part of the Arduino IDE, you need to edit the Theme.txt file which is at:
C:\arduino-1.8.13\lib\theme\theme.txt (Arduino was placed at C:\ on my machine)
Here is the edited part that controls the bottom pane (Console) and makes it use black text on white background:
Code:
# GUI - CONSOLE
console.font = Consolas,plain,12
console.font.macosx = Monaco,plain,10
console.color = #FFFFFF
console.output.color = #000000
console.error.color = #E34C00
In the sludge at the bottom of my memory is an old theory that programmers sometimes used low-contrast color pairs for console output because less expensive CRT-based monitors did not respond well to large changes in screen brightness due to poor black-level restoration circuits. Why low-contrast color pairs are still the default in the Arduino IDE in the 2020s is a mystery to me. The first thing I do with each new version of Arduino is to modify theme.txt to make the console black on white.