In 1996, CSS introduced margin, border and padding for many more elements. Width for the cell was defined as 'the suggested width for a cell content in pixels excluding the cell padding.' The only element to support padding in those early days was the table cell. On the other hand, the HTML width attribute of an image defined the width of the image itself (inside any border). The HTML width attribute of a table defined the width of the table including its border. However, it varied depending on the element. The difference in how width is interpreted between the W3C and Internet Explorer box modelsīefore HTML 4 and CSS, very few HTML elements supported both border and padding, so the definition of the width and height of an element was not very contentious. Similarly, the total height of a box equals top-margin + top-border + top-padding + height + bottom-padding + bottom-border + bottom-margin. The total width of a box is therefore left-margin + left-border + left-padding + width + right-padding + right-border + right-margin.

Before CSS3, this box model was known as W3C box model, in CSS3, it is known as the content-box.

the margin is the space around the borderĪccording to the CSS1 specification, released by W3C in 1996 and revised in 1999, when a width or height is explicitly specified for any block-level element, it should determine only the width or height of the visible element, with the padding, borders, and margins applied afterward.

the border is any kind of line (solid, dotted, dashed.) surrounding the box, if present.

the padding describes the space between this content and the border of the box.

the height and width describe dimensions of the actual content of the box (text, images.Each of those boxes has five modifiable dimensions: While the specification never uses the term 'box model' explicitly, the term has become widely used by web developers and web browser vendors.Īll HTML elements can be considered 'boxes', this includes div tag, p tag, or a tag.

Section 4 of the CSS1 specification defines a 'formatting model' that gives block-level elements-such as p and blockquote-a width and height, and three levels of boxes surrounding it: padding, borders, and margins. The Cascading Style Sheets (CSS) specification describes how elements of web pages are displayed by graphical browsers. 3 Support for Internet Explorer's box model.

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