Line height (known in print as leading) is the vertical space between lines of text. Incorrect line height ruins legibility.
The Inverse Proportion Rule:
As font size increases, relative line height must decrease.
1.4 to 1.6). When users read multi-line paragraphs, ample line height prevents the eye from accidentally skipping lines when returning to the left margin.1.1 to 1.25). At large sizes, a 150% line height spreads words so far apart that multi-line headings look like disconnected sentences.Level 3 · Design Tokens & Foundations