Oppo
Dark or Light Theme for the Phone App auf Oppo
The Phone app on Oppo devices running ColorOS can carry its own display setting instead of following the system-wide dark mode. That is why calls and the dialer sometimes stay bright even after you switch the rest of the interface to dark.
A dark theme reduces the amount of light emitted by the display, which is easier on your eyes in low-light situations. On devices with an OLED panel, it also lowers power draw, since darker pixels use less energy.
To change the theme, open Tap on Phone ➔ Open the Menu ➔ Tap on Settings ➔ Tap on Display options ➔ Tap on Choose theme ➔ Choose Light or Dark.
Pick whichever option suits your surroundings. If you switch the system-wide appearance later and the Phone app does not follow along, come back to this same menu and set it again.
This setting only affects the Phone app itself. Messages, contacts, and other apps keep their own theme settings and may need to be adjusted separately.