Main application part that communicates with the user. We sort the information from big to small.
Build the hierarchy to allow the user to navigate and consume content with ease.
Readable font size is imperative. Recommended size for reading is 16-17pt. Altough it may vary according to the font and device type.
Font line height is proportional to its size. Recommended ratio for the paragraph is 1:1.5. Exception: headlines that need smaller height line, the ratio is approximately at 1:1.24.
It is good to keep the text line length around 40-60 characters. In areas with broader line lengt paragraphs may contain up to 120 characters. In this case, you need bigger line spacing.
20-40 characters when lines are shorter.
Text blocks must contain an optimal number of lines and balanced width. Imagine that you put the heading and text inside a rectangle.