The 1910 design team posted some advice for optimal web typography on their blog. Some of it I’ve seen before, but rarely in such a concise yet helpful format. Here’s one of those “why didn’t I think of this myself” moments, regarding picking an optimal body text size:
If in doubt, just grab a camera and take a picture of the text from the desired viewing distance and compare this to a picture of a page from a regular textbook taken from 30 to 40 cm away. Alternatively hold the book somewhere between yourself and the screen while keeping one of your eyes closed. If the digital text is smaller than the printed one you’ll want to go bigger.