CSS ruby-merge Property Reference

The CSS ruby-merge property is a experimental property in CSS Ruby. Review its formal syntax, computed behavior, and practical declarations.

Updated 2026-08-12

ruby-merge overview

The CSS ruby-merge property is a experimental property in CSS Ruby. Review its formal syntax, computed behavior, and practical declarations.

The computed value normally inherits from the parent element when no declaration wins the cascade.

Syntax and formal definition

ruby-merge formal syntax

Field	Value
Formal syntax	separate \| collapse \| auto
Initial value	separate
Applies to	rubyAnnotationContainers
Inherited	Yes
Percentages	no
Computed value	asSpecified
Animation type	byComputedValueType
Media	visual
Specification group	CSS Ruby
Status	Experimental

Practical examples

These declarations demonstrate valid ways to set ruby-merge. The initial and inherit global keywords remain available even when a property-specific value is preferable.

ruby-merge live example

CSS

.reset-example {
  ruby-merge: initial;
}

.inherit-example {
  ruby-merge: inherit;
}

@supports (ruby-merge: initial) {
  .supported {
    ruby-merge: initial;
  }
}