Well, a fact is that Rujevica is planned as a training camp (still is) so stadium is actually expanded with northern stand after plans for building new stadium at K antrida has to be postponed because of lack of financing. Originally, Rujevica had only two stands and expansion was made in season after we won championship because UEFA regulations say that minimum capacity of a stadium which can be licensed for CL is 8.000.
Plan was that new K antrida stadium is planned for capacity of 14.000. Here it is:
https://www.stadion****rida.hr/en/stadion-****rida/
Also, there is peak into atmosphere on K antrida when it is full (friendly against Maribor 2018):
https://www.youtube.com/watch?v=IkVlyCYtKJo
And Rujevica, game against Cibalia for winning the championship 2017 (without northern stand):
https://www.youtube.com/watch?v=wGWQZRzdVjQ