Original sentence: Although the main intent of Vitezović was to prove that the borders of Croatia (back then part of the Habsburg Monarchy) were originally considerably larger, it grew into a political program based on a separate pan-South Slavic identity, related to the rebirth of the Croatian national idea, called Illyrian
Edited sentence: Although the main intent of Vitezović was to prove that the borders of Croatia (back then part of the Habsburg Monarchy) were originally considerably larger, it grew into a political programme based on identities of Illyrians, Slavs and Croats