Each unit in this pattern is a rounded rectangle housing a smaller rounded rectangle, then a third innermost frame, all stacked into rows held together by horizontally lined connector bands. The effect reads almost like a grid of windows or circuit panels depending on how you color the layers.

The three nested levels inside each cell give you a clear decision at every unit: warm center, cool frame, neutral band, or any inversion of that. This rounded rectangle grid coloring page sits at a moderate-to-dense complexity level, repetitive enough to feel meditative but varied enough in its layering to keep each row interesting.