CSS Box Model

The CSS Box Model

In CSS, the term "box model" is used when talking about web design and layout.

The CSS box model is essentially a box that wraps around every HTML element.

Every box consists of four parts: content, padding, borders and margins.

The image below illustrates the CSS box model:

Explanation of the different parts (from innermost part to outermost part):

• Content - The content of the box, where text and images appear
• Padding - Clears an area around the content. The padding is transparent
• Border - A border that goes around the padding and content
• Margin - Clears an area outside the border. The margin is transparent

The box model allows us to add a border around elements, and to define space between elements.

Width and Height of an Element

In order to set the width and height of an element correctly in all browsers, you need to know how the box model works.

Here is the calculation:

The total width of an element should be calculated like this:

Total element width = width + left padding + right padding + left border + right border

The total height of an element should be calculated like this:

Total element height = height + top padding + bottom padding + top border + bottom border