Layout de Página de Livro de Cálculo Moderno

Educational vertical textbook page redraw of a modern Chinese university calculus textbook, based on the layout and hierarchy of the reference image. The page features a clean double-column structure on bright white paper with crisp mathematical typesetting. Top left header displays page number "[214]", top right header shows chapter title "[Chapter 4 Applications of Derivatives]". Main section heading in cobalt blue reads "[4.3 Tangent Lines and Linear Approximation]". The body includes clear introductory text, light yellow definition callout boxes, mint green example boxes, and light blue sidebars. Mathematical diagrams feature sharp vector-style coordinate grids with blue function curves and red tangent lines, complete with tangent line formulas and linearization equations. Clean, professional, print-ready textbook aesthetic.