Submit your life to the dark side (or the light side).
You need a version of CrOS that supports changing themes. Make sure you are above version 106+.
If your on a older version, your stuck on dark.
You can update using a usb if your chromebook is still supported.
There are 2 modes. Light mode and dark mode.
There are also colour pallets which colour windows, the taskbar, and other things
You just need to right click the taskbar and click "Set Wallpaper & Style"
You will see a window pop up with options for a screen saver but we don't care.
Click the theme and colours you want to apply! (Auto is time-sensitive, so dark at night and light at day.)
You've reached the end of this guide.