*,*:before,*:after{box-sizing:border-box;margin:0;padding:0}:root{--board-size: min(85vh, 560px);--square-size: calc(var(--board-size) / 8);--light: #f0d9b5;--dark: #b58863;--selected: #829769;--legal-dot: rgba(0, 0, 0, .25);--last-move: rgba(255, 255, 50, .35);--check-bg: radial-gradient(ellipse at center, rgba(255, 0, 0, .6) 0%, rgba(255, 0, 0, 0) 70%);--accent: #769656;--bg: #312e2b;--sidebar-bg: #272522;--text: #f1f1f1;--text-muted: #999}body{font-family:Segoe UI,system-ui,-apple-system,sans-serif;background:var(--bg);color:var(--text);min-height:100vh;display:flex;justify-content:center;align-items:flex-start}#root{width:100%}.app{max-width:950px;margin:0 auto;padding:16px}.header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;padding-bottom:12px;border-bottom:1px solid rgba(255,255,255,.1)}.header h1{font-size:1.6rem;font-weight:700;letter-spacing:-.5px}.controls{display:flex;gap:12px;align-items:center}.difficulty-label{display:flex;align-items:center;gap:6px;font-size:.85rem;color:var(--text-muted)}.difficulty-label select{background:var(--sidebar-bg);color:var(--text);border:1px solid rgba(255,255,255,.15);border-radius:6px;padding:6px 10px;font-size:.85rem;cursor:pointer}.new-game-btn{background:var(--accent);color:#fff;border:none;padding:8px 18px;border-radius:6px;font-size:.9rem;font-weight:600;cursor:pointer;transition:background .15s}.new-game-btn:hover{background:#6a8a4c}.game-container{display:flex;gap:20px;align-items:flex-start}.board-section{display:flex;flex-direction:column;gap:4px}.board-wrapper{display:flex;gap:0}.rank-labels{display:flex;flex-direction:column;justify-content:space-around;padding-right:4px}.rank-label{height:var(--square-size);display:flex;align-items:center;justify-content:center;font-size:.75rem;color:var(--text-muted);width:16px}.file-labels{display:flex;justify-content:space-around;padding-left:20px;padding-top:2px}.file-label{width:var(--square-size);text-align:center;font-size:.75rem;color:var(--text-muted)}.board{display:grid;grid-template-columns:repeat(8,var(--square-size));grid-template-rows:repeat(8,var(--square-size));border-radius:4px;overflow:hidden;box-shadow:0 8px 32px #00000080}.square{width:var(--square-size);height:var(--square-size);display:flex;align-items:center;justify-content:center;position:relative;cursor:pointer;transition:background .1s}.square.light{background-color:var(--light)}.square.dark{background-color:var(--dark)}.square.selected{background-color:var(--selected)!important}.square.last-move{background-color:var(--last-move)}.square.light.last-move{background-color:#f5f682}.square.dark.last-move{background-color:#b9ca43}.square.in-check{background:var(--check-bg),var(--light)}.square.dark.in-check{background:var(--check-bg),var(--dark)}.square:hover{filter:brightness(1.08)}.piece{font-size:calc(var(--square-size) * .8);line-height:1;-webkit-user-select:none;user-select:none;pointer-events:none;filter:drop-shadow(1px 2px 2px rgba(0,0,0,.3));z-index:2}.legal-dot{width:calc(var(--square-size) * .3);height:calc(var(--square-size) * .3);border-radius:50%;background:var(--legal-dot);z-index:1}.legal-capture{position:absolute;top:0;right:0;bottom:0;left:0;border-radius:50%;border:calc(var(--square-size) * .1) solid var(--legal-dot);z-index:1}.sidebar{display:flex;flex-direction:column;gap:12px;width:220px;min-width:180px}.status{background:var(--sidebar-bg);border-radius:8px;padding:12px 16px;font-size:.95rem;font-weight:500;display:flex;align-items:center;gap:10px}.status.game-over{background:#76965640;border:1px solid var(--accent)}.status.in-check-status{background:#ff505026;border:1px solid rgba(255,80,80,.4)}.thinking-spinner{width:18px;height:18px;border:3px solid rgba(255,255,255,.2);border-top:3px solid var(--text);border-radius:50%;animation:spin .8s linear infinite;flex-shrink:0}@keyframes spin{to{transform:rotate(360deg)}}.move-history{background:var(--sidebar-bg);border-radius:8px;padding:12px 16px;max-height:420px;overflow-y:auto}.move-history h3{font-size:.85rem;color:var(--text-muted);margin-bottom:8px;text-transform:uppercase;letter-spacing:.5px}.move-list{display:flex;flex-direction:column;gap:2px}.move-row{display:flex;gap:4px;font-size:.85rem;font-family:SF Mono,Consolas,monospace;padding:2px 4px;border-radius:3px}.move-row:hover{background:#ffffff0d}.move-num{color:var(--text-muted);min-width:28px}.move-white,.move-black{min-width:60px}.captured-pieces{min-height:28px;display:flex;flex-wrap:wrap;gap:2px;padding:2px 20px}.captured-piece{font-size:1.1rem;opacity:.8}.modal-overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#0009;display:flex;align-items:center;justify-content:center;z-index:100;-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px)}.promotion-modal{background:var(--sidebar-bg);border:1px solid rgba(255,255,255,.15);border-radius:12px;padding:24px 32px;text-align:center}.promotion-modal h3{margin-bottom:16px;font-size:1.1rem}.promotion-options{display:flex;gap:8px}.promotion-btn{background:var(--dark);border:2px solid transparent;border-radius:8px;width:64px;height:64px;font-size:2.5rem;cursor:pointer;transition:all .15s;display:flex;align-items:center;justify-content:center}.promotion-btn:hover{border-color:var(--accent);background:var(--light);transform:scale(1.1)}.move-history::-webkit-scrollbar{width:6px}.move-history::-webkit-scrollbar-track{background:transparent}.move-history::-webkit-scrollbar-thumb{background:#ffffff26;border-radius:3px}@media (max-width: 720px){:root{--board-size: min(90vw, 400px)}.game-container{flex-direction:column;align-items:center}.sidebar{width:100%;max-width:calc(var(--board-size) + 20px)}.header{flex-direction:column;gap:10px;text-align:center}}