Approaches to scale widgets to fit various screen resolutions for mobile and desktop ?

[EdOfTheMountain]

Question:
Are there any system wide approaches to scale things like button widgets and such ? Should I be learning about style sheets?

Problem
I have a QWidget app that supports both desktops and Android, and iOS. Desktop deployment is fine.

The problem I wish to solve is when app is deployed on a Nexus 7" Android tablet, the widgets are too small to manipulate by finger touch. For example, the QTableWidget rows and vertical scroll bars are too small. For things like QFileDialog I expect I will need to implement a custom file browser that is more mobile friendly.

Thanks in advance for any tips or direction,

-Ed