Posted by Jim Higson on 09/29/05 17:25

talthen.z-serwera.o2@nospam.pl wrote:

> "Marc" <mbradshaw@beasolutions.com>
>> This exactly proves the point as to why invalid CSS should be ignored -
>> where here you intended IE to display an <hr> of width 80% of it's
>> parent, you in fact got an <hr> of width 80px.
>
> MSIE shows both lines as 80 % long. Mozilla and Opera show only first line
> as 80 % long. The second is about 2 or 3 pixels long. And the question is:
> why in pure html the space between 80 and % doesn't make a difference and
> in CSS it does?

Browsers tend to compensate for bad HTML more than bad CSS because the de
facto rules on what bad HTML to accept were created in the 'wild west'
early days of the web, when browser makers regularly disregarded the specs.

CSS support was added later, when the browser makers had learned from the
mistakes of the past to stick more closely to the spec. Today even IE7
looks like it will be pretty standards compliant.

Specifically, disregarding invalid CSS rules is good because it makes future
compatability easier. A CSS2 browser should still be able to make a good go
at rendering most of a CSS3 styled documents, even though it won't
recognise all the rules. If the CSS2 browser started trying to guess what
all the unrecognised rules meant there'd be chaos.

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