css box model explained code example

Example 1: how to make a box in html

<div style="width:500px;height:100px;border:1px solid #000;">This is a rectangle!</div>

Example 2: 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 3: 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