Quirks mode

Quirks mode is an alternate method by which modern web browsers render HTML. Its purpose is to replicate rendering behavior introduced in previous versions of the browsers (mostly Netscape 4, which had really bad CSS standard support, and Internet Explorer 4 which was better but still not close), which attempted to implement CSS to their own specifications. This allows for older web sites to still render as intended while allowing new sites to utilize standards-compliant CSS.

Quirks mode may be triggered in a web browser by leaving out the Document Type Definition from the beginning of the document.

=Most significant changes=

Quirks mode changes BoxModel of CSS. In Quirks mode width is sum of objects width, padding and border. In opposite, W3C box model, width is just width.

Quirks mode allows unitless CSS lengths, assuming that every number represents number of pixels. Standard CSS requires all lengths to have units.

=External links=

*[http://www.quirksmode.org/css/quirksmode.html Quirksmode.org: Quirks mode and strict mode]