More Crosshairs, Fullscreen on Mac!

Adding Light colored crosshairs to fix #104 (thanks @z-f-s!)

I've re-enabled Fullscreen on MacOS! Your mileage may vary but things seem to be working 👍 Fixes #106 (thanks @The-Minecraft-Scientist!)

I've also bumped the max size from 100px to 125px, I'll try to get around to a better 4k experience soon. but this should help.