Quirks Mode and Strict Mode
Web browsers use two general types of rendering modes: “quirks” mode and “strict” mode. They are invoked by the presence or absence of certain document type declarations, which are described generally in Chapter 2 and listed on this book’s companion website.
Instead of treating box properties additively,
as strict mode does and the CSS 2.1 box model suggests, quirks
mode rendering uses stated width and
height as the primary reference for
computing element dimensions, and subtracts the other
box values from those as appropriate. These behaviors are analogous to the
behavior of the CSS3 box-sizing property,
which has two values: content-box and
border-box.
Note
Quirks mode rendering is the only rendering mode available in versions of Internet Explorer prior to IE 6.
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