Flexbox, Responsive design

What challenges did you encounter, and how did you overcome them?

I faced the challenge to style tables, I was not able to styling as I wanted but it look a lot like the solution, I tried different approaches to styling the table but not able to avoid unexpected behavior while editing the th elements.

What specific areas of your project would you like help with?

Styling tables to avoid undesired behavior in this case for desktop design it was not possible for me to add padding to th elements without having td elements moved.

Also I would like to have advice on how can I handle font sizing to be responsive, how should I handle fonts sizes without using pixels and text to adapt to different sizes.