ruby-align

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

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

/* 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;

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

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

See also

• HTML Ruby elements: <ruby>, <rt>, <rp>, and <rtc>.
• CSS Ruby properties: ruby-position, ruby-merge.