The padding-bottom CSS property sets the height of the padding area on the bottom of an element.
How To Work with the Box Model in CSS
CSS Cascade Style Sheet
Introduction to the CSS basic box model - CSS: Cascading Style Sheets
CSS Padding - Coding Ninjas
tutorialspoint - CSS Cascade Style Sheets
qph.cf2.quoracdn.net/main-qimg-6c03300c2182bea3875
Css, PDF, Typefaces
Cascading style sheet
CSS padding using simple CSS - Cascading Style Sheets Tutorial