:root{--bg-primary: #1a1a2e;--bg-secondary: #16213e;--bg-card: #1e2a45;--bg-card-hover: #253352;--bg-board: #0f3460;--accent: #b1624d;--accent-hover: #c97a66;--accent-light: rgba(177, 98, 77, .15);--red-piece: #e74c3c;--red-piece-bg: #2c1810;--black-piece: #1a1a2e;--black-piece-text: #ecf0f1;--text-primary: #ecf0f1;--text-secondary: #8892a4;--text-muted: #5a6478;--border: rgba(255, 255, 255, .06);--border-light: rgba(255, 255, 255, .1);--success: #2ecc71;--danger: #e74c3c;--warning: #f39c12;--font-main: "Inter", "Noto Sans SC", system-ui, sans-serif;--font-chinese: "Noto Sans SC", "SimHei", sans-serif;--radius: 12px;--radius-sm: 8px;--radius-xs: 4px;--transition: all .2s ease;--transition-slow: all .4s ease}*{margin:0;padding:0;box-sizing:border-box}body{font-family:var(--font-main);background:var(--bg-primary);color:var(--text-primary);min-height:100vh;overflow-x:hidden}.app-header{display:flex;align-items:center;justify-content:space-between;padding:8px 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