:root{font-family:Inter,ui-sans-serif,system-ui,sans-serif;color:#17324d;background:#edf3f4;font-synthesis:none}*{box-sizing:border-box}body{margin:0;min-width:320px}button{border:0;border-radius:12px;padding:.8rem 1.1rem;font:inherit;font-weight:700;color:#17324d;background:#dbe6e8;cursor:pointer;touch-action:manipulation}button:hover:not(:disabled),button:focus-visible{background:#c6d9dd;outline:3px solid #e8b84c;outline-offset:2px}button:disabled{cursor:not-allowed;opacity:.45}select{width:100%;margin:0 0 1rem;padding:.75rem;border:2px solid #c6d9dd;border-radius:12px;color:#17324d;background:#fff;font:inherit;font-weight:700}.app-shell{min-height:100vh}.topbar{display:flex;justify-content:space-between;align-items:center;gap:1rem;padding:1.25rem clamp(1rem,5vw,4rem);background:#17324d;color:#fff}.eyebrow{margin:0 0 .3rem;color:#e8b84c;font-size:.78rem;font-weight:800;letter-spacing:.12em;text-transform:uppercase}.topbar h1{margin:0;font-size:clamp(1.35rem,3vw,2rem)}nav{display:flex;gap:.4rem;flex-wrap:wrap;justify-content:flex-end}.nav-button{padding:.65rem .8rem;color:#fff;background:transparent}.nav-button.active{background:#31546e}.game-layout{display:grid;grid-template-columns:minmax(0,1fr) minmax(240px,320px);gap:clamp(1.25rem,4vw,4rem);align-items:center;max-width:1180px;margin:0 auto;padding:clamp(1rem,5vw,4rem)}.board-panel{width:100%;min-width:0}.board-wrap{width:100%;max-width:720px;margin:auto;border:10px solid #fff;border-radius:10px;box-shadow:0 14px 35px #17324d22;overflow:hidden}.game-panel{min-width:0;padding:1rem 0}.game-panel h2{margin:0 0 1rem;font-size:clamp(1.7rem,4vw,2.6rem)}.status{padding:1rem;border-radius:14px;background:#fff;font-weight:800;font-size:1.1rem}.status-checkmate{background:#dff0cf}.status-draw,.status-stalemate{background:#f8e9bd}.help{line-height:1.55}.actions{display:flex;gap:.65rem;flex-wrap:wrap;margin-top:1.5rem}.primary{color:#fff;background:#26735a}.primary:hover:not(:disabled){background:#1e604b}.move-count{color:#60747d}.placeholder{max-width:620px;margin:10vh auto;padding:2rem;text-align:center}.placeholder h2{font-size:2rem}.modal-backdrop{position:fixed;top:0;right:0;bottom:0;left:0;display:grid;place-items:center;padding:1rem;background:#17324dbb}.promotion-dialog{width:min(100%,420px);padding:2rem;border-radius:20px;background:#fff;box-shadow:0 20px 50px #0004}.promotion-options{display:grid;grid-template-columns:repeat(2,1fr);gap:.7rem;margin-top:1.2rem}@media(max-width:760px){.topbar{align-items:flex-start;flex-direction:column}.topbar nav{width:100%;justify-content:flex-start}.game-layout{display:block;padding:1rem}.board-wrap{width:min(96vw,620px);border-width:5px}.game-panel{max-width:620px;margin:1rem auto 0}.game-panel h2{font-size:1.8rem}}.error{padding:.75rem;border-radius:12px;color:#8c2f39;background:#fbe2e2}