How ruby overhangs text
With -ah-ruby-overhang, you can specify how the ruby overhangs adjacent text of its base. When ruby length is longer than the base character, the maximum overhang length can be specified with -ah-ruby-limit-overhang. Alternatively, the ruby text can be condensed, with the limit specified by -ah-ruby-condense. Also, when ruby length is shorter than the base character, the spacing before and after ruby can be specified with -ah-ruby-limit-space.

-ah-ruby-overhang (How ruby overhangs adjacent text of its base)

Example of specifying ‘none’ (Does not to overhang adjacent text of its base), ‘start’ (Overhangs adjacent text on the start side of its base) and ‘end’ (Overhangs adjacent text on the end side of its base):
-ah-ruby-overhang: none;
あ 燕 つばめ あ
-ah-ruby-overhang: start;
あ 燕 つばめ あ
-ah-ruby-overhang: end;
あ 燕 つばめ あ
Example of specifying ‘except-kanji’ (Does not overhang adjacent text if it is kanji) and ‘except-katakana’ (Does not overhang adjacent text if it is katakana):
-ah-ruby-overhang: except-kanji
あ 燕 つばめ 阿
-ah-ruby-overhang: except-katakana
あ 燕 つばめ ア
Example of specifying ‘except-start-open-parenthesis’ (Does not overhang adjacent text if the start side of its base is an opening parenthesis) and ‘except-end-close-parenthesis’ (Does not overhang adjacent text if the end side of its base is a closing parenthesis):
-ah-ruby-overhang: except-start-open-parenthesis;
( 燕 つばめ あ
-ah-ruby-overhang: except-end-close-parenthesis;
あ 燕 つばめ )

-ah-ruby-limit-overhang (Maximum length of ruby to overhang adjacent text of its base when the ruby length is longer than its base)

Example of specifying the maximum overhang length as a number (a value multiplied by the font size of ruby), length (specified length) and percentage (a value multiplied by the font size):
-ah-ruby-limit-overhang: 1.0; (Initial)
あ 燕 つばめ あ
-ah-ruby-limit-overhang: 0; (Initial)
あ 燕 つばめ あ

-ah-ruby-condense (Whether to condense ruby text when the ruby length is longer than its base)

Example of specifying the font condense limit as ‘none’ (do not condense ruby text), a number (a value multiplied by the font size of ruby) and a percentage (a value multiplied by the font size):
-ah-ruby-condense: none; (Initial)
あ 燕 つばめ あ
-ah-ruby-condense: 0.75; (Initial)
あ 燕 つばめ あ

-ah-ruby-limit-space (Maximum spacing before and after ruby text when the ruby length is shorter than its base character)

Example of specifying the maximum ruby spacing as a number (a value multiplied by the font size of ruby), length (specified length) and percentage (a value multiplied by the font size). When ‘none’ is specified, the maximum spacing before and after ruby will not be limited.
-ah-ruby-limit-space: 1.0; (Initial)
なげきの聖母像 ピエタ
-ah-ruby-limit-space: 0;
なげきの聖母像 ピエタ
-ah-ruby-limit-space: none;
なげきの聖母像 ピエタ