Nice contrast for active element. But these wooden support planks look like the bark is still on them. They could be made more wood-looking by increasing the length of radial section lines.

Wood is actually a quite complex subject

"Sapwood is the living, outermost portion of a woody stem or branch, while heartwood is the dead, inner wood, which often comprises the majority of a stem’s cross-section. You can usually distinguish sapwood from heartwood by its lighter color.

But, color in wood can be very misleading; not all heartwood is dark and not all dark-colored wood is heartwood. And, the relative amounts of sapwood and heartwood in any stem can vary greatly among individuals, species, and growing conditions."