Generate a Zen mandala design with a simpler structure, focusing on broader sections and fewer intricate details to ensure clear areas for coloring. The mandala should be fully centered on an 8.5 x 8.5 inches page, with all design elements contained well within the page margins, especially on the left and right sides. Emphasize symmetry and balance in the design, ensuring the central part of the mandala is clearly defined and easily distinguishable. Include ample space around the mandala for adding mindfulness quotes later. Aim for a high-resolution, monochromatic line art with clean, bold lines suitable for coloring. The design should evoke a sense of calm and focus, suitable for meditation