Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The line-height-step CSS property sets the step unit for line box heights. When the property is set, line box heights are rounded up to the closest multiple of the unit.

/* Point values */
line-height-step: 18pt;

/* Global values */
line-height-step: inherit;
line-height-step: initial;
line-height-step: revert;
line-height-step: revert-layer;
line-height-step: unset;


The line-height-step property is specified as any one of the following:

  • a <length>.



The specified <length> is used in the calculation of the line box height step.

Formal definition

Initial value0
Applies toblock containers
Computed valueabsolute <length>
Animation typediscrete

Formal syntax


Setting step unit for line box height

In the following example, the height of line box in each paragraph is rounded up to the step unit. The line box in <h1> does not fit into one step unit and thus occupies two, but it is still centered within the two step unit.

:root {
  font-size: 12pt;
  --my-grid: 18pt;
  line-height-step: var(--my-grid);
h1 {
  font-size: 20pt;
  margin-top: calc(2 * var(--my-grid));

The result of these rules is shown below in the following screenshot:

How the line-height-step property affects the appearance of text.


CSS Rhythmic Sizing
# line-height-step

Browser compatibility

BCD tables only load in the browser

See also