The "background-clip" property

A diagram of three boxes with dashed borders, with their backgrounds clipped to the border-box, padding-box, and content-box.

By default, backgrounds cover the entire border-box (they are applied underneath the border as well), but their background-position (and also %-based background-size) is relative to the padding-box.

[…]

We can make the background cover just the padding-box or just the content-box with the help of background-clip.

Source link

The `background-clip` Property and its Use Cases | CSS-Tricks