42. for legible body text, optimal line length is 60-70 characters per line. no fewer than 35, no greater than 80. going longer than these ranges makes it difficult for the eye to track back to the beginning of each line. go shorter and reading becomes stuttered, like reading a telegram. or a toot.
43. The web, and UI frameworks will fight you on this, but if you establish a vertical rhythm in your typographic grid, you’ll increase the feeling of unity in the design and help the eye flow better across the design. Choose a verrical spacing that suits the size and style of your main text font. there’s no hard and fast rules, but it’s good to aim for the vertical spacing to be around 1.33-1.5 the point size of your body text. heading sizes can be neat integer multiples of 1/2 or 1/3 of main