TITLE: Chroma — Colour Palette Studio FILE: 071-palette-studio.html === PROMPT (exact prompt used) === Build "Chroma — Color Palette Studio", an elegant tool for generating harmonious palettes. A clean white UI (#ffffff, #f4f4f5 panels, #18181b text). The main view is five tall colour columns filling the screen (horizontal bands on mobile); each shows hex, RGB, HSL and a name (nearest match from a curated list of ~150 named colours) and has lock, copy and adjust controls. Space (or a button) generates a new palette that respects locked colours using harmony rules — analogous, complementary, split-complementary, triadic, tetradic, monochromatic — computed in OKLCH for perceptual evenness (implement the conversion). Extra panels: a WCAG AA/AAA contrast checker for text on each colour; a live preview card (a mini UI mockup) using the palette; a gradient preview; and export (CSS variables, JSON) copied to the clipboard. Interaction: drag columns to reorder, click a hex to edit it, and a colour-wheel diagram showing the harmony geometry with draggable points. Smooth colour transitions. Typography: a crisp sans plus monospace. SHARED REQUIREMENTS (apply to every page in this 100-page collection): 1. One standalone HTML5 file. All CSS inline in