maidosu dont need to go to systembolaget if u just wanna buy light beers. u can buy it in any grocery stores but the strongest alcohol beers found in any grocery stores are 3.5%. any higher than that are only allowed to be sold on systembolaget
heres example of one the store from ica selling beers
https://www.icaekangen24.se/c-464-l.aspx
Never seen a beer have 3.5% it sounds like something they'll make specially to go around the rules :D