Our games are played on both tiny mobile phones as well as on large tablets. On small screens, the user interface, like the clock and book, has to be relatively large. In extreme cases, up to 50% of the whole screen. This relation would look ridiculous on large screens where 10% is more than enough and gives the user a much larger area to play on.
To change the size, flip one page back while playing, to show the settings. Drag the multi-directional arrows to change the size and position of the user interface.