In Design Elements: Typography Fundamentals, Cullen writes:
Type for the web, as well as digital devices and gestural interfaces, meet challenges because conditions vary, unlike fixed mediums such as print. Multiple browsers, platforms, and screen sizes present type differently. Typefaces suited to one might not suit another. Expect the unexpected in digital realms. Be flexible and responsive. Digital formats know no bounds. Unlimited virtual space offers potential unseen in other areas.