Screens & cards
The primary display of the Memento mobile edition is as a full screen display — one which occupies the full app space on the device, but leaves the notification bar visible and accessible. This is how most modern Android apps are displayed.
Some Memento displays can optionally be displayed as cards, which may or may not occupy only a portion of the screen, showing a bit of the underlying screen behind it. The user may choose by pressing a button for a card to occupy the entire screen or only a portion of it. Using a card gives the user a sense of the card as being modal, or temporary & subordinate to the outer screen. Cards make sense when the device display is large enough for the data to be readily visible, but may be inconvenient on smaller devices, hence the toggle button.