should be under accessibility settings where you can change the color of the 4 AND the opacity of the numbers.
personally i'd change the color of the number 4 to white since ik finding an 8 in these kinda games would be hella rare. (8 is also white)
yoo i just beat the game. lowkey the best excavation game i've played on itch.io so far (or the first game i've really tried here.)
