W3C home > Mailing lists > Public > www-style@w3.org > February 2012

Re: [css3-values] Physical length units

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Sun, 19 Feb 2012 09:15:33 -0800
Message-ID: <CAAWBYDAuCyxX93xV9dDGzY57Th-w_b5hEkDco0jHMrU_yxq6Ww@mail.gmail.com>
To: Matthew Wilcox <elvendil@gmail.com>
Cc: Boris Zbarsky <bzbarsky@mit.edu>, www-style@w3.org
On Sun, Feb 19, 2012 at 9:03 AM, Matthew Wilcox <elvendil@gmail.com> wrote:
> None of which mitigates the fact that physical measures are wrong in CSS.
> I know this isn't fixable whilst keeping backward compatibility. I
> also think it's a pretty crazy position to be in.
> Oh to be able to declare a version of CSS to author against. We'd be
> able to fix these inconsistencies.
> On 19 February 2012 15:54, Boris Zbarsky <bzbarsky@mit.edu> wrote:
>> On 2/19/12 9:30 AM, Matthew Wilcox wrote:
>>> The fact that cm etc don't result in those units is what is super
>>> confusing. Why in the world would any author expect 1cm to *not* be
>>> 1cm, and know to use 1trucm instead?
>> They may not.  But they expect 12pt to be 16px, not actually 12pt.  They
>> expect this because that's what every single word processor they used did
>> and what most browsers did.
> And how many people, in the wild, are using pt for screen CSS at the moment?
> Serious question by the way. I'd have imagined very few (I've never
> come across it).

Lots.  It's largely people using the pt unit for fonts, but the other
units show up at times, and people expect them to have a dependable
ratio with px.  (Actually, they expect them to have the same ratio as
whatever they see on their dev box's screen.)

>> Furthermore, authors tend to code by copy and paste as well as
>> guess-and-check.  This is good because it allows someone with minimal HTML
>> or CSS knowledge to create web pages, but bad because it means that when
>> someone writes "12pt" chances are they didn't _mean_ anything; they just
>> wrote something that worked.
>> OK, so your options are then as follows:
>> 1)  Make 12pt actually be 1/6 of a physical inch.  This has been tried, and
>> it breaks pages.
> I imagine it does. But that's still the right thing to do. The problem
> is CSS's inability to use specified versions. "fixing this breaks
> current sites" is getting a pretty annoying thing to keep reading. So,
> fix CSS to behave better? These things are only going to stack up the
> longer we use CSS.

You should really go read the debates from when this was formally
decided.  I'm pretty sure we exhausted the state-space of questions
and objections.  Literally everything you've said, at least, has been
said before, and already answered or argued against.

Received on Sunday, 19 February 2012 17:16:20 UTC

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