You can swap between light and dark themes and find out which theme suits your eyes better. Once logged in, just click on your account name at the top right and choose your designated preference.
To elevate the setup more, you can go to profile, settings, and then choose a theme per device.
Choose which color theme you want to use on the forum. This theme will be linked to your account and applies to all your devices unless you toggle on the switch below for per-device settings.