The Equilateral Triangle of a Perfect Paragraph | Better Web Type
This is a fun game (I scored a measly 73/100). The idea is to develop a feeling for the balance between font-size, line-height, and line length …just like the three sides of an equilateral triangle.
Too many of them still set line-height, font size and line width as independent features when in fact they should all be considered together. The equilateral triangle is a perfect representation of how the three features work in harmony.