
The curb is the thing that comes out.
The raised edge is cut out. The floor is sloped to a linear drain near the glass, then waterproofed, then tiled. Honed stone, so the floor stays comfortable when it is wet.
A bench can be built into the stone. A handheld sits on a slide bar. Wood goes in the wall before the tile, so a bar can be added later without opening the shower again.

