Air Carrier Captain reported an opposite direction departing aircraft took off over them as they were taking the runway for takeoff. Captain indicated the intensity of the runway lights obscured their ability to see the opposite direction traffic who had not made calls on CTAF.

Narrative

Pushed off the gate and got our clearance while still in the ramp area. When ready to taxi. We made a radio call with the intent to taxi to and takeoff of runway 31 on CTAF 118.3 because tower was closed. We finished all checks up to before takeoff below the line before we crossed runway 3/21 to mitigate distractions while crossing. We made another radio call before we crossed runway 3/21. we got to the end of runway 31. I called for the before takeoff below the line before we started to taxi onto the runway. When that check was complete. I Made the appropriate call outs. Final was clear and runway looked clear from our point of view. At the angle we were at the bright runway edge lights were like a wall of light. we started taxiing onto the runway. that's when we could see the other aircraft lights and they took off over us. Never heard them make a radio call. Cause: The runway edge lights creating a wall of light from our point of view at the end of the runway definitely made it so we couldn't see the end of the other runway. Also no radio communication from the other aircraft. maybe the other aircraft just assumed they were alone. Suggestions: We made at least 6 radio calls. So I don't think more radio calls would have changed anything. But the runway lights were at high intensity. the aircraft departing the runway had dimmer lights than the runway lights so it was harder to see the aircraft. turning down the airport light intensity may have helped us see the other aircraft better before entering the runway.