Add Sliven (Bulgaria) to your list and use my-locations table to visually convert it's time to another timezone or city time.
Mouse over the colored hour-tiles and glance at the hours selected by the column.

Current time zone for Sliven (Bulgaria) is EEST, whose offset is GMT+3 from Greenwich Mean Time (GMT).

The IANA timezone identifier for Sliven, Bulgaria is "Europe/Sofia"

DST started on Sunday, March 30 2025 at 3:00 am local time, when time in Sliven moved forward 1 hour to 4:00 am.
DST ends on Sunday, October 26 2025 at 4:00 am local time, when time in Sliven moves back 1 hour to 3:00 am.