Below/above bridge[]
Feel free to replace the stairs on layer 2 with vertical slabs, or completely remove them (allowing for a viewing "window"). If you remove the stairs, you can also replace the purpur blocks on layer 2 with vertical End Rods.
For the above-bridge design, move the rails to layer 4 and remove the stairs on layer 2.
All stairs are facing inwards, toward the bridge.
Stairs on layer 1 and 4 are upright, whereas stairs on layer 2 are upside-down.
Beside bridge[]
All stairs are upright and facing inwards.
Slabs are vertical slabs on the side closer to the rails.