:root {
            --primary: #3498db;
            --primary-dark: #2980b9;
            --secondary: #95a5a6;
            --danger: #e74c3c;
            --success: #2ecc71;
            --warning: #f39c12;
            --bg: #f5f7fa;
            --card: #ffffff;
            --text: #2c3e50;
            --text-light: #7f8c8d;
            --border: #e1e8ed;
            --shadow: 0 2px 12px rgba(0,0,0,0.08);
            --radius: 12px;
            --cell-size: 52px;
            --grid-gap: 1px;
            --grid-bg: #34495e;
        }
        
        * { margin: 0; padding: 0; box-sizing: border-box; }
        a {text-decoration: none;}
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
            background: var(--bg);
            color: var(--text);
            line-height: 1.6;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
        }
        
        /* ==================== 导航栏 ==================== */
        .navbar {
            background: var(--card);
            box-shadow: var(--shadow);
            position: sticky;
            top: 0;
            z-index: 100;
        }
        
        .nav-container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 60px;
        }
        
        .logo {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary);
            text-decoration: none;
            display: flex;
            align-items: center;
            gap: 8px;
        }
        
        .logo svg { width: 32px; height: 32px; }
        
        .nav-links {
            display: flex;
            gap: 8px;
            list-style: none;
        }
        
        .nav-links a {
            text-decoration: none;
            color: var(--text-light);
            padding: 8px 16px;
            border-radius: 20px;
            transition: all 0.3s;
            font-size: 0.95rem;
            font-weight: 500;
        }
        
        .nav-links a:hover, .nav-links a.active {
            background: var(--primary);
            color: white;
        }
        
        .menu-toggle {
            display: none;
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: var(--text);
        }
        
        /* ==================== 主内容区 ==================== */
        .main-container {
            max-width: 1000px;
            margin: 0 auto;
            padding: 30px 20px;
            flex: 1;
            width: 100%;
        }
        
        .page-header {
            text-align: center;
            margin-bottom: 24px;
        }
        
        .page-header h1 {
            font-size: 1.8rem;
            margin-bottom: 6px;
            color: var(--text);
        }
        
        .page-header p {
            color: var(--text-light);
            font-size: 1rem;
        }
        /* ==================== 底部语言切换（圆形字母样式） ==================== */
        .footer-section {
            background: var(--card);
            padding: 30px 20px;
            border-top: 1px solid var(--border);
            margin-top: auto;
        }
        
        .footer-container {
            max-width: 800px;
            margin: 0 auto;
            text-align: center;
        }
        
        .lang-section {
            margin-bottom: 20px;
        }
        
        .lang-section h3 {
            font-size: 0.9rem;
            color: var(--text-light);
            margin-bottom: 16px;
            font-weight: 600;
            text-transform: uppercase;
            letter-spacing: 1px;
        }
        
        .lang-buttons {
            display: flex;
            gap: 12px;
            justify-content: center;
            flex-wrap: wrap;
        }
        
        .lang-btn {
            width: 44px;
            height: 44px;
            border-radius: 50%;
            border: 2px solid var(--border);
            background: transparent;
            cursor: pointer;
            font-size: 0.85rem;
            font-weight: 700;
            transition: all 0.3s;
            color: var(--text-light);
            display: flex;
            align-items: center;
            justify-content: center;
            text-transform: uppercase;
        }
        
        .lang-btn:hover { 
            border-color: var(--primary); 
            color: var(--primary); 
            background: rgba(52, 152, 219, 0.05);
            transform: scale(1.1);
        }
        
        .lang-btn.active { 
            background: var(--primary); 
            border-color: var(--primary); 
            color: white; 
            box-shadow: 0 4px 12px rgba(52, 152, 219, 0.3);
        }
        
        .footer-info {
            color: var(--text-light);
            font-size: 0.85rem;
            line-height: 1.6;
        }
        
        .footer-info p {
            margin-bottom: 6px;
        }
        /* ==================== Toast 提示 ==================== */
        .toast {
            position: fixed;
            top: 80px;
            left: 50%;
            transform: translateX(-50%) translateY(-100px);
            background: var(--text);
            color: white;
            padding: 12px 24px;
            border-radius: 8px;
            font-weight: 600;
            box-shadow: 0 4px 20px rgba(0,0,0,0.2);
            opacity: 0;
            transition: all 0.3s;
            z-index: 2000;
            pointer-events: none;
        }
        
        .toast.show {
            opacity: 1;
            transform: translateX(-50%) translateY(0);
        }
        
        .toast.success { background: var(--success); }
        .toast.error { background: var(--danger); }
        /* ==================== 响应式设计 ==================== */
        @media (max-width: 768px) {
            :root { --cell-size: 42px; }
            
            .nav-links { display: none; }
            .menu-toggle { display: block; }
            
            .nav-links.mobile-open {
                display: flex;
                flex-direction: column;
                position: absolute;
                top: 60px;
                left: 0;
                right: 0;
                background: var(--card);
                padding: 16px;
                box-shadow: var(--shadow);
            }
            
            .page-header h1 { font-size: 1.5rem; }
            

        }
        
        @media (max-width: 480px) {
            :root { --cell-size: 36px; }
            
            .main-container { padding: 20px 12px; }
            

            
            .lang-btn {
                width: 40px;
                height: 40px;
                font-size: 0.8rem;
            }
        }
        
        @media (prefers-color-scheme: dark) {
            :root {
                --bg: #1a1a2e;
                --card: #16213e;
                --text: #e94560;
                --text-light: #a0a0a0;
                --border: #0f3460;
                --grid-bg: #0f3460;
            }

        }