Superfast night ferries strange departing time for travel day

I’m planning to take the boat from igoumenitsa to Bari on the night of the 19th of July. My issue is that the site says they depart at 23:59 which is 1 minute before midnight. Does the 19th of July still count as the travel day for the boat or can you just take the 20th as a travel day and combine it with the trains I’m taking later that day? Would love to hear some advice!