Please add a dark theme to the Android application. Because using your application at night or in dark rooms is very unpleasant because of the bright white background. Also in Android 10, a dark theme is implemented at the system level. And ideally, I would like to have a choice of gray (#121212) and black (#000000) backgrounds, since the black background looks better on devices with an AMOLED screen. Useful links: https://developer.android.com/guide/topics/ui/look-and-feel/darktheme, https://material.io/develop/android/theming/dark/, https://material.io/design/color/dark-theme.html.