wood-grain.jpg — "Fine Grained Wood" by Rob Tuytel, Poly Haven (https://polyhaven.com/a/fine_grained_wood)
License: CC0 (Public Domain). Free to use, no attribution required. Recolored in CSS per frame species.
wood-grain-h.jpg — the same texture rotated 90° (horizontal grain), for the top/bottom rails so the grain
turns at each mitered corner. Same CC0 source/license.
