I would like to call your attention to the darker strip of wood you can see between the carpet on the stairs & the wainscoting. Most will know this as the skirtboard. These are made from poplar because the homeowner was supposed to "paint" them white, the normal treatment.

Being the big thinker though, he elected to stain them (one on each side of the stairway) to match the oak. Close enough?

The one element that I am very proud of on these skirts is that they were scribed & cut to fit an existing set of stairs. They don't cap the ends, oh no! They are cut to fit the rise and run of the treads and precisely fit the radius on the fronts of the treads. No small feat for sure.