# Edit Grub bootmenu
sudo grub-mkconfig
sudo nano /etc/default/grub

# Add os-prober for dual boot+
# Remove "#" in Grub infront of os-prober
sudo os-prober

# Save updated grub config to grub
sudo grub-mkconfig -o /boot/grub/grub.cfg

# Menu colours
# Change inside /etc/defaults/grub
GRUB_TERMINAL_OUTPUT="gfxterm"
GRUB_COLOR_NORMAL="light-blue/black"
GRUB_COLOR_HIGHLIGHT="light-cyan/blue"
# JPG file has to exist in /boot/grub/
GRUB_BACKGROUND="/boot/grub/AI-Hoshino-Oshi-No-Ko.jpg"