i want to make a box outside a box css 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: 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