The orangewhitepda was an early approach to offer support for small screen devices. It hardly ever has been used as I know.
The huge font sizes I have used to get better legibility when you set your device to render the table cells below each other. In the other themes the font size gets very small.
If you may creat a more actual and better solution you may consider giving it back to the Moodle community and we can see if we replace orangewhitepda.