Label months & days
User feedback has shown, that the months & days need to be labeled. Not every user recognized the grid as some sort of calendar, and that the orientation changed if used on smaller devices. It might also be helpful to highlight the current day, which could be hard to find if a user starts using the diary later in the year.
For desktops, a simple hover effect could be added that displays the labels at the edges of the diary. But for mobile devices we would need to add some sort of delay. The labels should be display when opening the diary and then fade away after a certain amount of time. Only displaying them again, if the user touches any UI element.