allow relative font size for sub and sup to be set independently; sup…

…port combined setting for backwards compatibility

CHANGELOG.adoc

@@ -9,6 +9,7 @@ For a detailed view of what has changed, refer to the {url-repo}/commits/main[co
 
 Improvements::
 
+* allow relative font size for sub and sup to be set independently; support combined setting for backwards compatibility
 * allow value of `base-font-size-min` and `<category>-font-size-min` theme keys to be relative (e.g., 0.75em) (#2547)
 
 == 2.3.19 (2024-10-11) - @mojavelinux

lib/asciidoctor/pdf/ext/prawn/formatted_text/arranger.rb

@@ -9,7 +9,7 @@ def initialize *_args
     super
     @dummy_text = ?\u0000
     @normalize_line_height = false
-    @sub_and_sup_relative_size = 0.583
+    @sub_relative_size = @sup_relative_size = 0.583
   end
 
   def format_array= array
@@ -38,13 +38,18 @@ def preview_joined_string
   end
 
   def apply_font_size size, styles
-    if (subscript? styles) || (superscript? styles)
+    if (sub = subscript? styles) || (superscript? styles)
       size ||= @document.font_size
+      if instance_variable_defined? :@sub_and_sup_relative_size
+        relative_size = @sub_and_sup_relative_size
+      else
+        relative_size = sub ? @sub_relative_size : @sup_relative_size
+      end
       if String === size
         units = (size.end_with? 'em', '%') ? ((size.end_with? '%') ? '%' : 'em') : ''
-        size = %(#{size.to_f * @sub_and_sup_relative_size}#{units})
+        size = %(#{size.to_f * relative_size}#{units})
       else
-        size *= @sub_and_sup_relative_size
+        size *= relative_size
       end
       @document.font_size(size) { yield }
     elsif size