How to edit default CSS values

Hi, How can I edit default CSS values, for example H1/H6 font sizes? Overall, is there a way on the interface to set default values for specific tags or is it done via CSS? Thank you!

In Bootstrap, headings are set by default to values in rems (for example H1 is 2.5rem,) so if you increase or decrease the base font size in the HTML exaample... html { font-size: 14px; }

it will change all the headings correspondingly.

If you want specific heading sizes, you have to write custom CSS rules.