Because a sect of Croatia fans are Nazi sympathizers and burned a swastika into the pitch in Split in 2016.
https://talksport.com/football/431574/why-england-vs-croatia-behind-closed-doors-stadium-empty-fans/ Also How Croatia turned on activist accused of reporting fans’ racism Croatia must face Italy behind closed doors because of fresh racism by their fans but the country’s FA is blaming an anti-racism observer, who denies reporting the incidents, rather than the supporters https://www.theguardian.com/football/2015/apr/23/croatia-racism-italy-behind-closed-doors
Hahaha I remember something about this story and the www pro nazi salute awhile ago. This just cracks me up Za dom spremni