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ruby-align

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

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

/* 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: unset;

Initial value	`space-around`
Applies to	ruby bases, ruby annotations, ruby base containers, ruby annotation containers
Inherited	yes
Media	visual
Computed value	as specified
Animation type	discrete
Canonical order	the unique non-ambiguous order defined by the formal grammar

Syntax

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 syntax

start | center | space-between | space-around

Examples

This HTML will render differently with each value of ruby-align:

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

Ruby aligned at the start of the base text

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

ruby {
  ruby-align:start;
}

This gives the following result:

Ruby aligned at the center of the base text

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

ruby {
  ruby-align:center;
}

This gives the following result:

Extra space distributed between ruby elements

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

ruby {
  ruby-align:space-between;
}

This gives the following result:

Extra space distributed between and around ruby elements

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

ruby {
  ruby-align:space-around;
}

This gives the following result:

Specifications

Specification	Status	Comment
CSS Ruby Layout Module Level 1 The definition of 'ruby-align' in that specification.	Working Draft	Initial definition

Browser compatibility

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	No	No¹	38	No²	No	No

Feature	Android webview	Chrome for Android	Edge mobile	Firefox for Android	IE mobile	Opera Android	iOS Safari
Basic support	No	?	?	38	No	No	No

1. Edge supports an earlier draft of CSS Ruby with non-standard values for this property: auto, left, center, right, distribute-letter, distribute-space, and line-edge.

2. Internet Explorer 9 and later supports an earlier draft of CSS Ruby with non-standard values for this property: auto, left, center, right, distribute-letter, distribute-space, and line-edge.

¹ Microsoft Edge and its predecessor Internet Explorer—versions 9 through 11—implement an early draft of CSS Ruby where the ruby-align property had the values auto, left, center, right, distribute-letter, distribute-space, and line-edge. Here is a table describing approximate equivalency between the Microsoft implementations and the current CSS Ruby, Level 1 specification:

Edge and IE Syntax	Standard Syntax
`auto`	`space-around` (default value) for ideographic scripts or `center` for Latin scripts; to achieve a similar effect, one may use ISO 15924 script codes in conjunction with HTML `lang` attributes or XML `xml:lang` attributes and CSS `lang` pseudo‑class selectors
`left`	`start` in left‐to‐right scripts
`center`	`center` without the optional behavior described in CSS Ruby, Level 1, Section 5.2: Line‐Edge Alignment; this is the Firefox behavior
`right`	`start` in right‐to‐left scripts
`distribute-letter`	`space-between`
`distribute-space`	`space-around` (default value)
`line-edge`	`center` with the optional behavior described in CSS Ruby, Level 1, Section 5.2: Line‐Edge Alignment; Firefox does not support a keyword for this behavior; CSS rules targeting individual `ruby` elements with the `center` and `start` keywords based on ruby base text positions and widths may be used instead to achieve similar effects in Firefox

ruby-align

Syntax

Values

Formal syntax

Examples

Ruby aligned at the start of the base text

Ruby aligned at the center of the base text

Extra space distributed between ruby elements

Extra space distributed between and around ruby elements

Specifications

Browser compatibility

See also