[OpenFontLibrary] CSS cascades: substituting typefaces with different appearing sizes

[Ben Weiner]

Hi all,

When doing print design layouts, I frequently find that substituting one 
typeface for another results in a need to increase or decrease the type 
size I have chosen by one or two points.

This happens for two reasons:

1. the typefaces have a different ratio of x-height to ascender height
2. one of the typefaces is 'bigger on the body' than the other. In other 
words, its ascenders and descenders come closer to touching the 
invisible top and bottom boundaries containing each letter. In effect, 
the bigger typeface is 'scaled up' in comparison to the smaller.

In the case of print/PDF design this is no problem, because the designer 
has complete control over the
typeface choice (unless she or he forgets to embed* the font in a PDF. 
So the final result is  the right typeface in the right point size.

In the case of a web page, the substitute typeface might need to be 
bigger or smaller; more likely, it might need more or less line feed. 
But there is no way to change the parameters of a CSS rule based on the 
typeface (font-family) selected by the browser from a cascade like

  font-family: "My Cool Sans", "Trebuchet" sans-serif;

I wonder if anyone has thoughts about this.

Cheers,
Ben



* embedding really happens in PDFs. But not in web pages, I think.