Basic css tips in ionic mobile development

Hi,

I’m pretty new in mobile development using Ionic Framework.
Since we are using CSS to make designs, what are your tips to make sure the styles will work fine in all devices? Do you prefer percentage or is it OK to hard-code pixel sizes?
Here are some points to discuss:

  • Centering (of a form, or a div) on the screen, percentage or pixels or something else?
  • Setting font sizes, percentage or pixels or something else?
  • Setting margin/padding sizes, percentage or pixels or something else?