Indeed, the most early Slavic settlements in Croatia indeed are around Knin area… besides, old Pagania was basically a heavily Slavic settled part in Dalmatia… Slavic migration in Dalmatia was the first one, the second one was in panonia…however don’t forget that Croatia was than fractioned, Dalmatia and panonian Croatia were two separate regions… the lone fact that the first king was from Dalmatia doesn’t mean Dalmatia is more heavily “Slavic”… Dalmatia is an more Illyrian-Slavic mixture, while Panonia is a bit more Slavic but still has an notable Illyrian influx as cities as Sisak were Celtic-Illyrian cities etc.  As for the most blue eyed and light haired people from Croatia, they come from Zagorje and Međimurje region, they even have an scandianvian-like phenotypes (light hair and red beard + long skulled, with medium skeleton height)…though there’s a lot more such light phenotypes among Dalmatian islanders rather then the Dalmatian coast-liners.
I mean, no point discussing this since there’s both kind of phenotypes in south as well as in north… but roughly i’d say people from Zagore, Međimurje, east-Slavonia and Dalmatian islands have a strong notable light phenotypes no matter if they’re Germanic or Slavic in origin.

In addition, i noticed a light phenotype among city people of Šibenik and Zadar in Dalmatia, while darker phenotype around city people of Makarska and nearby areas…