- Debug CrossRef.

- Miscellaneous improvements.

Manual.cls

@@ -4,14 +4,13 @@
 	published by Prime Controls.
 }
 
-% Option 'electronic': single side printing.
+% Option 'electronic': single side printing, among other things.
 \bool_new:N \g_electronic_bool
 \bool_gset_false:N \g_electronic_bool
 
 \DeclareOption{electronic}{
 	\bool_gset_true:N \g_electronic_bool
 }
-
 \NewExpandableDocumentCommand{\IsElectronic}{}{\g_electronic_bool}
 
 % Option 'admin': turn on admin manual sections.
@@ -21,17 +20,16 @@
 \DeclareOption{admin}{
 	\bool_gset_true:N \g_admin_bool
 }
-
 \NewExpandableDocumentCommand{\IsAdminManual}{}{\g_admin_bool}
 
-% Option 'darkmode': render as light text on dark background.
+% Option 'darkmode': render as light text on dark background. Only applies if
+% electronic mode is also on.
 \bool_new:N \g_dark_mode_bool
 \bool_gset_false:N \g_dark_mode_bool
 
 \DeclareOption{darkmode}{
-	\bool_gset_true:N \g_dark_mode_bool
+	\bool_gset:Nn \g_dark_mode_bool {\g_electronic_bool}
 }
-
 \NewExpandableDocumentCommand{\IsDarkMode}{}{\g_dark_mode_bool}
 
 % Option 'draft': same as base book class, but with bigger overfull boxes.
@@ -42,17 +40,16 @@
 	\bool_gset_true:N \g_draft_bool
 	\overfullrule = 1in
 }
-
 \NewExpandableDocumentCommand{\IsDraft}{}{\g_draft_bool}
 
-% Option 'roman': render Part numbers as Roman numerals.
+% Option 'roman': render Part numbers and print-format front matter page numbers
+% as Roman numerals.
 \bool_new:N \g_roman_bool
 \bool_gset_false:N \g_roman_bool
 
 \DeclareOption{roman}{
 	\bool_gset_true:N \g_roman_bool
 }
-
 \NewExpandableDocumentCommand{\DoRomanNumerals}{}{\g_roman_bool}
 
 % Option 'labels': show Part and Chapter labels in the header.
@@ -62,7 +59,6 @@
 \DeclareOption{labels}{
 	\bool_gset_true:N \g_label_bool
 }
-
 \NewExpandableDocumentCommand{\ShowLabels}{}{\g_label_bool}
 
 \DeclareOption*{\PassOptionsToClass{\CurrentOption}{book}}