Typekit Practice

Values to which metrics should be changed are unique to each font file

Tim Brown for Typekit:

We’re constantly learning, but here’s what we know right now: Windows browsers use Win metrics, Mac browsers use hhea metrics, and Firefox on Linux uses Typo metrics unless the hhea values are greater. Win and hhea metrics must match, including an hhea linegap of zero. Typo linegap has to be zero too, or lines of text are spaced unpredictably across browsers. The specific values to which metrics should be changed are unique to each font file. Our internal tools for foundry partners make recommendations based on the conditions I just mentioned, and also based on the maximum ascent/descent of glyphs in the font file.