Ruby

“Ruby” are annotations meant to provide additional meaning or specify the pronunciation of a text segment.
They are mainly used in Asian languages (Chinese, Japanese, Korean).

Standard properties (to use)

Property	Description
`ruby-align`	Defines the alignment of ruby text relative to the base (e.g., `start`, `center`, `space-between`).
`ruby-position`	Defines the position of the ruby annotation (`over`, `under`, `inter-character`). Example: text above, below, or between characters.

Deprecated or non-standard properties

Property	Status	Explanation
`ruby-overhang` (sometimes written as `ruby-overhang.php` in old docs)	Deprecated, never standardized	Property specific to Internet Explorer/Opera for handling ruby text spacing. Not supported today.

Usage example

<ruby>
  漢 <rt>kan</rt>
  字 <rt>ji</rt>
</ruby>

ruby {
  ruby-align: center;
  ruby-position: over;
}

Result: the phonetic annotation (furigana) appears above the characters.

Key takeaways

The ruby-align and ruby-position properties are standardized and useful for Asian typography.
ruby-overhang was an experimental IE/Opera property, now abandoned and should not be used.
Ruby annotations improve readability and linguistic accessibility, especially for learning Japanese (furigana) and Chinese (pinyin).