CSS Box Model

CSS Box Model is a CSS module that defines the rectangular boxes, including their padding and margin, that are generated for elements and laid out according to the visual formatting model.

Reference

Properties

Guides and tools

Introduction to the CSS box model (en-US)

Explains one of the fundamental concept of CSS, the box model: describes the meaning of the margin, padding, as well as the different areas of a box.

Mastering margin collapsing

In several cases, two adjacent margins are collapsed into one. This article describes when this is happening and how to control it.

Box-shadow generator (en-US)

An interactive tool that allows to visually create shadows and to generate the needed syntax for the box-shadow property.

Specifications

Specification
CSS Box Model Module Level 3