In a few words:
250 of the 300 seats are allocated proportionally among the parties that got over 3% of the vote. The remaining 50 go to the first party.
250 of the 300 seats are allocated proportionally among the parties that got over 3% of the vote. The remaining 50 go to the first party.
In fact, because the allocation of parliament seats is calculated on the basis of the total vote and because of the adjustments that this entails for the allocation of constituency seats, you can be the first party in a constituency and yet get fewer seats in that constituency than the second party.