edit the provided staircase interior rendering add a traditional white closed stringer skirt board structure underneath both stair runs similar to the reference image keep the existing staircase layout wood handrails black metal balusters wall molding windows flooring and architecture exactly the same the white skirt board should follow the stair angle cleanly along both flights and around the landing giving the staircase a realistic structurally supported appearance instead of a floating look maintain ultra realistic architectural photography quality with natural lighting and accurate proportions
