Gutenberg is a flexible and simple–to–use web typography starter kit for web designers and developers. It’s a small step towards a better typography on the web. Beautiful typographic styles can be made by setting base type size, line-height (leading) and measure (max-width).
The reader should be able to read the message of a text easily and comfortably. This depends to a not inconsiderable extent on the size of the type, the length of the lines and the leading.—Josef Mueller–Brockmann
Gutenberg sets the baseline grid to establish a proper vertical rhythm and makes sure all elements fit into it. It sets up the macro typography so you can focus on the micro–typographic details.