In addition to the default light mode, Submitty supports a number of other themes like ‘Dark Mode’, ‘Black Mode’. You can choose any of these theme from the “Change theme” drop-down given on the “My profile” page
If your device uses an AMOLED screen, you may want to enable the black mode as well. This will save battery life. Once you enable dark mode, the option to enable black mode will appear. Click the “Enable Black Mode” checkbox to switch.