The parent section is the section that contains this section. A special
case are sections of type GTK_CSS_SECTION_DOCUMENT. Their parent will
either be NULL if they are the original CSS document that was loaded by
[method@Gtk.CssProvider.load_from_file] or a section of type
GTK_CSS_SECTION_IMPORT if it was loaded with an @import rule from
a different file.
Gets the parent section for the given section.
The parent section is the section that contains this section. A special case are sections of type GTK_CSS_SECTION_DOCUMENT. Their parent will either be NULL if they are the original CSS document that was loaded by [method@Gtk.CssProvider.load_from_file] or a section of type GTK_CSS_SECTION_IMPORT if it was loaded with an @import rule from a different file.