ruby-align

Baseline 2024

Newly available

Since ⁨December 2024⁩, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

The ruby-align CSS property defines the distribution of the different ruby elements over the base.

Syntax

css

/* Keyword values */
ruby-align: start;
ruby-align: center;
ruby-align: space-between;
ruby-align: space-around;

/* Global values */
ruby-align: inherit;
ruby-align: initial;
ruby-align: revert;
ruby-align: revert-layer;
ruby-align: unset;

Values

start: Is a keyword indicating that the ruby will be aligned with the start of the base text.
center: Is a keyword indicating that the ruby will be aligned at the middle of the base text.
space-between: Is a keyword indicating that the extra space will be distributed between the elements of the ruby.
space-around: Is a keyword indicating that the extra space will be distributed between the elements of the ruby, and around it.

Formal definition

Initial value	`space-around`
Applies to	ruby bases, ruby annotations, ruby base containers, ruby annotation containers
Inherited	yes
Computed value	as specified
Animation type	by computed value type

Formal syntax

ruby-align = 
  start          |
  center         |
  space-between  |
  space-around

Examples

Ruby aligned at the start of the base text

HTML

html

<ruby>
  <rb>This is a long text to check</rb>
  <rp>（</rp><rt>short ruby</rt><rp>）</rp>
</ruby>

CSS

css

ruby {
  ruby-align: start;
}

Result

Ruby aligned at the center of the base text

HTML

html

<ruby>
  <rb>This is a long text to check</rb>
  <rp>（</rp><rt>short ruby</rt><rp>）</rp>
</ruby>

CSS

css

ruby {
  ruby-align: center;
}

Result

Extra space distributed between ruby elements

HTML

html

<ruby>
  <rb>This is a long text to check</rb>
  <rp>（</rp><rt>short ruby</rt><rp>）</rp>
</ruby>

CSS

css

ruby {
  ruby-align: space-between;
}

Result

Extra space distributed between and around ruby elements

HTML

html

<ruby>
  <rb>This is a long text to check</rb>
  <rp>（</rp><rt>short ruby</rt><rp>）</rp>
</ruby>

CSS

css

ruby {
  ruby-align: space-around;
}

Result

Specifications

Specification
CSS Ruby Annotation Layout Module Level 1 # ruby-align-property

Browser compatibility

Help improve MDN

Learn how to contribute

This page was last modified on ⁨Oct 30, 2025⁩ by MDN contributors.

View this page on GitHub • Report a problem with this content