lineheights

Line height refers to the vertical distance between the baselines of successive lines of text in a block. In traditional typography this spacing is called leading, historically achieved with strips of lead placed between lines. In digital typesetting and web design, line height is controlled by the line-height property and related spacing rules.

Line height can be specified as an absolute measure (for example in pixels or points) or as a relative value. In CSS, it is common to use a unitless multiplier (such as 1.4) that multiplies the element’s font size, or a length value (such as 20px or 1.6em). The resulting vertical space determines how much white space appears between lines.

Appropriate line height enhances readability by reducing crowding and improving the visual rhythm of text. Values that are too small cause overlapping ascenders and descenders, while values that are too large create excessive space and disrupt the flow. For body text, many designers aim for a line height around 1.4 to 1.6 times the font size, with adjustments based on font family, line length, and audience.

Practical considerations include font metrics (family, weight), column width, and the overall page layout. Accessibility guidelines often encourage comfortable line spacing to improve legibility for readers with visual or cognitive differences. Line height remains a fundamental, tuneable aspect of typography and responsive design, bridging traditional craft and modern web standards.