css margin border padding content code example
Example 1: padding margin and border
GO TO THIS LINK
https://www.geeksforgeeks.org/css-margins-padding/
https://media.geeksforgeeks.org/wp-content/uploads/cssmarginandpadding.png
Example 2: css box model
MDN (Mozilla Developer Network)
Probably the best place for an in-depth explanation of
web related technologies.
See the link below regarding the CSS BOX MODEL