/* --- 全局基础样式 --- */
        * { margin: 0; padding: 0; box-sizing: border-box; }
        body {
            font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
            background-color: #121212;
            color: #e0e0e0;
            line-height: 1.6;
        }
        .container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

        /* --- 导航栏 --- */
        header {
            background: rgba(30, 30, 30, 0.95);
            padding: 20px 0;
            border-bottom: 1px solid #333;
            position: sticky; top: 0; z-index: 100;
            backdrop-filter: blur(10px);
        }
        .nav-content { display: flex; justify-content: space-between; align-items: center; }
        .logo { font-size: 24px; font-weight: bold; color: #fff; letter-spacing: 1px; }
        .download-btn-small {
            background: #fff; color: #000; padding: 8px 20px;
            text-decoration: none; border-radius: 4px; font-weight: bold; font-size: 14px;
            transition: all 0.3s ease;
        }
        .download-btn-small:hover { background: #ccc; }

        /* --- Hero 区域 (首屏) --- */
        .hero {
            text-align: center; padding: 80px 0;
            background: radial-gradient(circle at center, #2a2a2a 0%, #121212 70%);
        }
        .hero h1 { font-size: 48px; margin-bottom: 20px; color: #fff; }
        .hero p { font-size: 18px; color: #aaa; margin-bottom: 40px; max-width: 600px; margin-left: auto; margin-right: auto; }
        .cta-buttons { display: flex; justify-content: center; gap: 20px; }
        .btn {
            padding: 15px 30px; border-radius: 8px; text-decoration: none; font-weight: bold;
            display: inline-block; transition: transform 0.2s;
        }
        .btn-primary { background: #fff; color: #000; }
        .btn-secondary { border: 1px solid #fff; color: #fff; }
        .btn:hover { transform: translateY(-2px); }

        /* --- 通用区块标题 --- */
        .section-title {
            text-align: center; font-size: 32px; margin-bottom: 50px; color: #fff;
            position: relative; padding-bottom: 15px;
        }
        .section-title::after {
            content: ''; position: absolute; bottom: 0; left: 50%; transform: translateX(-50%);
            width: 60px; height: 3px; background: #fff;
        }

        /* --- 市场行情展示区 (模拟数据) --- */
        .market-section { padding: 60px 0; background: #181818; }
        .market-grid {
            display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 20px;
        }
        .coin-card {
            background: #252525; padding: 20px; border-radius: 12px;
            border: 1px solid #333; display: flex; justify-content: space-between; align-items: center;
        }
        .coin-info h3 { font-size: 18px; color: #fff; margin-bottom: 5px; }
        .coin-info span { font-size: 14px; color: #888; }
        .coin-price { text-align: right; }
        .price-val { display: block; font-size: 18px; font-weight: bold; color: #fff; }
        .price-change { font-size: 14px; font-weight: bold; }
        .up { color: #0ecb81; } /* 涨绿 */
        .down { color: #f6465d; } /* 跌红 */

        /* --- 银行级安全保障 (您关注的区域) --- */
        .security-section { padding: 80px 0; background: #121212; }

        /* 关键修复：使用 Grid 布局确保等宽，并使用 Flex 居中内容 */
        .security-grid {
            display: grid;
            grid-template-columns: repeat(4, 1fr); /* 强制分为4列 */
            gap: 20px;
        }

        .feature-card {
            background: #1e1e1e;
            border: 1px solid #333;
            border-radius: 8px;
            padding: 30px 20px;
            text-align: center;

            /* 【核心修复代码】：让卡片内部内容垂直+水平居中 */
            display: flex;
            flex-direction: column;
            justify-content: center; /* 垂直居中 */
            align-items: center;     /* 水平居中 */
            min-height: 220px;       /* 设置最小高度，保证卡片看起来一样大 */
        }

        .feature-card h3 {
            font-size: 20px; color: #fff; margin-bottom: 15px;
            font-weight: 600;
        }
        .feature-card p {
            font-size: 14px; color: #aaa; line-height: 1.5;
        }

        /* --- C2C 交易优势 --- */
        .c2c-section { padding: 80px 0; background: #181818; }
        .c2c-container { display: flex; flex-wrap: wrap; justify-content: center; gap: 40px; }
        .c2c-item { flex: 1; min-width: 300px; max-width: 500px; }
        .c2c-item h3 { font-size: 24px; margin-bottom: 15px; color: #fff; }
        .c2c-item p { color: #bbb; margin-bottom: 20px; }
        .tag {
            display: inline-block; background: #333; color: #fff;
            padding: 5px 10px; border-radius: 4px; font-size: 12px; margin-right: 10px; margin-bottom: 10px;
        }

        /* --- 页脚 --- */
        footer { background: #000; padding: 40px 0; text-align: center; border-top: 1px solid #333; }
        footer p { color: #666; font-size: 14px; }

        /* --- 响应式适配 (手机端) --- */
        @media (max-width: 900px) {
            .security-grid {
                grid-template-columns: repeat(2, 1fr); /* 平板变2列 */
            }
        }

        @media (max-width: 600px) {
            .hero h1 { font-size: 32px; }
            .security-grid {
                grid-template-columns: 1fr; /* 手机变1列 */
            }
            .feature-card {
                min-height: auto; /* 手机上取消固定高度，自适应内容 */
                padding: 25px;
            }
            .nav-content { flex-direction: column; gap: 15px; }
        }