Re: [CSSWG] Resolutions 2007-08-28

On Saturday 2007-09-01 16:01 +0200, Christoph Päper wrote:
> Philip Taylor:
> >Bert Bos wrote:
> >But what about the standard typographic guidance, extended to the  
> >web screen, that a single line of text in a paragraph should not  
> >exceed approximately
> >$nn$ characters (40 -- 70 for paper, 70 -- 100 for screen)?
> 
> That guidance is based on human "psychoptical" properties. It  
> manifests in a rule of thumb expressed in number of characters, but  
> it really is about visual angles. When you increase the character  
> size the ideal viewing distance gets larger, too. The usual viewing  
> distance for paper and screen differ, as does character detail.

I don't see what it has to do with visual angles.  (Though I'd agree
that visual angle is often what really matters about character
size.)

I think the primary motivation for that rule is that when there are
too many characters on a line, it's hard to see the right line to go
to when jumping from the end of one line to the start of the next.
Thus the advice is often combined with advice that lines with higher
numbers of characters should have higher line spacing.

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/