Responsive CSS Grid Layout with Sticky Header and Collapsible Sidebar

Write a responsive CSS grid layout with [grid_columns] columns on desktop, [tablet_columns] on tablet, and single column on mobile. Include a sticky header with [header_height], a collapsible sidebar that toggles via [toggle_method], and a main content area. Use CSS Grid with named grid areas, smooth transitions (0.3s ease), and breakpoints at [mobile_breakpoint]px and [tablet_breakpoint]px. The sidebar should overlay content on mobile, push content on desktop, and maintain [sidebar_width] width. Include CSS custom properties for theming and ensure accessibility with proper focus states.