How to remember in CSS that margin is outside the border, and padding inside [closed]

Answer 1

Create yourself a commented base stylesheet which you can use as a template whenever you need to create a new site or edit an existing site.

You can add to it as you grow in knowledge and apply it to various different browsers to see how various things behave.

You'll also be able to add in comments or examples about other hard to remember stuff or stuff that is counter intuitive.