Pocket has an app-wide Dark Theme to make reading a pleasure at night, in addition to a low-contrast Sepia Theme.
To enable these themes, open an article, and tap the "AA" button. Then, tap the Themes button to toggle between Light, Dark and Sepia Themes.
When Dark Theme is enabled, it will affect the entire app, making the lists and menus are dark as well. This is excellent for nighttime reading.