Fluid Layouts with Golden Ratio Grid Proportioning

Act as a Classical Design Theorist and UI Developer. Construct a visually breathtaking, highly responsive Tailwind CSS layout mathematically dictated by the Golden Ratio (1.618). Initialize a main wrapper strictly capped at a max-width of [CONTAINER_WIDTH]. You must physically divide the CSS grid into a primary reading area and a secondary navigation sidebar utilizing the exact mathematical proportion of [PRIMARY_COL_WEIGHT] to [SECONDARY_COL_WEIGHT] (e.g., 1.618 to 1). Do not use approximations; implement this by injecting Tailwind's arbitrary grid values (e.g., `grid-cols-[1.618fr_1fr]`). Guarantee the layout remains perfectly fluid, dynamically squashing the sidebar into an off-canvas menu utilizing standard Tailwind breakpoints (`md:`, `lg:`) to protect the reading experience on tablets and mobile.