Is the diagonal white/black separator in the example supposed to indicate something? It appears to suggest something like "night" towards the right, and it line

Is the diagonal white/black separator in the example supposed to indicate something? It appears to suggest something like "night" towards the right, and it lines up with the numbers, but the numbers on either side of it are different, ranging from 10am/11am to 9pm/10pm. Edit: Oh! Is it just showing how the UI appears in dark mode? Then the diagonal is meaningless and distracting!