:root {
            --tr7nn-primary: #4285F4;
            --tr7nn-secondary: #EA4335;
            --tr7nn-tertiary: #FBBC04;
            --tr7nn-quaternary: #34A853;
            --tr7nn-text-main: #202124;
            --tr7nn-text-sub: #5f6368;
            --tr7nn-bg-light: #ffffff;
            --tr7nn-bg-gray: #f8f9fa;
            --tr7nn-shadow: 0 4px 20px rgba(0,0,0,0.08);
            --tr7nn-radius: 16px;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            -webkit-font-smoothing: antialiased;
        }

        body {
            font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            color: var(--tr7nn-text-main);
            line-height: 1.6;
            background-color: var(--tr7nn-bg-light);
            overflow-x: hidden;
        }

        /* 布局基础 */
        .tr7nn-container {
            max-width: 1100px;
            margin: 0 auto;
            padding: 0 24px;
            width: 100%;
        }

        /* 导航栏 */
        .tr7nn-header {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 1000;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(0,0,0,0.05);
            height: 72px;
            display: flex;
            align-items: center;
        }

        .tr7nn-nav {
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            align-items: center;
            width: 100%;
            min-width: 0;
        }

        .tr7nn-logo {
            display: flex;
            align-items: center;
            min-width: 0;
        }

        .tr7nn-logo img {
            height: 32px;
            width: auto;
        }

        .tr7nn-menu {
            display: flex;
            flex-wrap: wrap;
            list-style: none;
            gap: 24px;
            min-width: 0;
        }

        .tr7nn-menu li {
            min-width: 0;
        }

        .tr7nn-menu a {
            text-decoration: none;
            color: var(--tr7nn-text-sub);
            font-size: 14px;
            font-weight: 500;
            transition: color 0.3s;
            white-space: nowrap;
        }

        .tr7nn-menu a:hover {
            color: var(--tr7nn-primary);
        }

        .tr7nn-menu a.tr7nn-active {
            color: var(--tr7nn-primary);
            position: relative;
        }

        .tr7nn-menu a.tr7nn-active::after {
            content: '';
            position: absolute;
            bottom: -8px;
            left: 0;
            width: 100%;
            height: 2px;
            background: var(--tr7nn-primary);
        }

        /* Hero登录区 */
        .tr7nn-hero {
            padding: 160px 0 96px;
            background: radial-gradient(circle at 90% 10%, rgba(66, 133, 244, 0.05), transparent),
                        radial-gradient(circle at 10% 90%, rgba(52, 168, 83, 0.05), transparent);
        }

        .tr7nn-hero-grid {
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            gap: 64px;
        }

        .tr7nn-hero-content {
            flex: 1;
            min-width: 320px;
            word-break: break-word;
            overflow-wrap: break-word;
        }

        .tr7nn-hero-title {
            font-size: clamp(2rem, 4vw + 0.5rem, 3.5rem);
            line-height: 1.2;
            font-weight: 700;
            margin-bottom: 24px;
            color: var(--tr7nn-text-main);
            word-break: keep-all;
        }

        .tr7nn-hero-subtitle {
            font-size: clamp(1rem, 1.2vw + 0.5rem, 1.25rem);
            color: var(--tr7nn-text-sub);
            margin-bottom: 32px;
            line-height: 1.6;
        }

        /* 登录卡片 */
        .tr7nn-login-wrapper {
            flex: 0 0 420px;
            min-width: 320px;
        }

        .tr7nn-login-card {
            background: #ffffff;
            padding: 48px;
            border-radius: 24px;
            box-shadow: 0 20px 40px rgba(0,0,0,0.06);
            border: 1px solid rgba(0,0,0,0.03);
            text-align: center;
            transition: transform 0.3s ease;
        }

        .tr7nn-login-card:hover {
            transform: translateY(-5px);
        }

        .tr7nn-card-header {
            margin-bottom: 32px;
        }

        .tr7nn-card-header h2 {
            font-size: 24px;
            margin-bottom: 8px;
        }

        .tr7nn-input-group {
            margin-bottom: 20px;
            text-align: left;
        }

        .tr7nn-input-group input {
            width: 100%;
            padding: 16px;
            border: 1px solid #dadce0;
            border-radius: 8px;
            font-size: 16px;
            transition: border-color 0.3s, box-shadow 0.3s;
            outline: none;
        }

        .tr7nn-input-group input:focus {
            border-color: var(--tr7nn-primary);
            box-shadow: 0 0 0 3px rgba(66, 133, 244, 0.1);
        }

        .tr7nn-btn-primary {
            width: 100%;
            padding: 16px;
            background: var(--tr7nn-primary);
            color: white;
            border: none;
            border-radius: 8px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: background 0.3s, transform 0.2s;
            margin-top: 12px;
        }

        .tr7nn-btn-primary:hover {
            background: #3367d6;
            transform: scale(1.02);
        }

        .tr7nn-login-footer {
            margin-top: 24px;
            font-size: 14px;
            color: var(--tr7nn-text-sub);
        }

        .tr7nn-login-footer a {
            color: var(--tr7nn-primary);
            text-decoration: none;
        }

        /* 安全矩阵区块 */
        .tr7nn-section {
            padding: 96px 0;
        }

        .tr7nn-section-title {
            text-align: center;
            margin-bottom: 64px;
        }

        .tr7nn-section-title h2 {
            font-size: clamp(1.5rem, 3vw, 2.5rem);
            margin-bottom: 16px;
        }

        .tr7nn-security-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
            gap: 32px;
        }

        .tr7nn-security-card {
            background: var(--tr7nn-bg-gray);
            padding: 32px;
            border-radius: var(--tr7nn-radius);
            transition: all 0.3s ease;
            min-width: 0;
            word-break: break-word;
        }

        .tr7nn-security-card:hover {
            background: #fff;
            box-shadow: var(--tr7nn-shadow);
        }

        .tr7nn-status-badge {
            display: inline-block;
            padding: 4px 12px;
            border-radius: 20px;
            font-size: 12px;
            font-weight: 600;
            margin-bottom: 16px;
            background: rgba(52, 168, 83, 0.1);
            color: var(--tr7nn-quaternary);
        }

        .tr7nn-security-card h3 {
            font-size: 18px;
            margin-bottom: 12px;
            color: var(--tr7nn-text-main);
        }

        .tr7nn-security-card p {
            font-size: 14px;
            color: var(--tr7nn-text-sub);
            line-height: 1.7;
        }

        /* 极速同步区块 - 创意插图替代区 */
        .tr7nn-sync-section {
            background: #202124;
            color: #fff;
            border-radius: 40px;
            margin: 48px auto;
            padding: 80px 48px;
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            gap: 48px;
        }

        .tr7nn-sync-visual {
            flex: 1;
            min-width: 300px;
            display: flex;
            justify-content: center;
            align-items: center;
        }

        /* CSS 绘制的同步艺术图 */
        .tr7nn-sync-art {
            position: relative;
            width: 240px;
            height: 240px;
            border: 2px dashed rgba(255,255,255,0.2);
            border-radius: 50%;
            animation: tr7nn-rotate 20s linear infinite;
        }

        .tr7nn-sync-dot {
            position: absolute;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background: #fff;
        }

        .tr7nn-dot-1 { top: -20px; left: 50%; transform: translateX(-50%); background: var(--tr7nn-primary); }
        .tr7nn-dot-2 { bottom: -20px; left: 50%; transform: translateX(-50%); background: var(--tr7nn-secondary); }
        .tr7nn-dot-3 { left: -20px; top: 50%; transform: translateY(-50%); background: var(--tr7nn-tertiary); }
        .tr7nn-dot-4 { right: -20px; top: 50%; transform: translateY(-50%); background: var(--tr7nn-quaternary); }

        @keyframes tr7nn-rotate {
            from { transform: rotate(0deg); }
            to { transform: rotate(360deg); }
        }

        .tr7nn-sync-info {
            flex: 1.2;
            min-width: 320px;
        }

        /* 页脚 */
        .tr7nn-footer {
            background: var(--tr7nn-bg-gray);
            padding: 64px 0;
            border-top: 1px solid rgba(0,0,0,0.05);
        }

        .tr7nn-footer-top {
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            gap: 48px;
            margin-bottom: 48px;
        }

        .tr7nn-footer-brand h2 {
            font-size: 24px;
            font-weight: 700;
            color: var(--tr7nn-text-main);
            margin-bottom: 16px;
        }

        .tr7nn-footer-links {
            display: flex;
            flex-wrap: wrap;
            gap: 64px;
        }

        .tr7nn-link-col h4 {
            font-size: 14px;
            text-transform: uppercase;
            letter-spacing: 1px;
            margin-bottom: 20px;
            color: var(--tr7nn-text-main);
        }

        .tr7nn-link-col ul {
            list-style: none;
        }

        .tr7nn-link-col li {
            margin-bottom: 12px;
        }

        .tr7nn-link-col a {
            text-decoration: none;
            font-size: 14px;
            color: var(--tr7nn-text-sub);
            transition: color 0.3s;
        }

        .tr7nn-link-col a:hover {
            color: var(--tr7nn-primary);
        }

        .tr7nn-footer-bottom {
            padding-top: 32px;
            border-top: 1px solid rgba(0,0,0,0.05);
            display: flex;
            flex-wrap: wrap;
            justify-content: space-between;
            align-items: center;
            font-size: 12px;
            color: var(--tr7nn-text-sub);
        }

        /* 响应式断点 */
        @media (max-width: 768px) {
            .tr7nn-header { height: auto; padding: 16px 0; }
            .tr7nn-menu { display: none; } /* 移动端建议用汉堡菜单，此处简化 */
            .tr7nn-hero { padding: 120px 0 64px; }
            .tr7nn-hero-grid { flex-direction: column; text-align: center; }
            .tr7nn-login-wrapper { flex: 1 0 100%; width: 100%; }
            .tr7nn-sync-section { padding: 48px 24px; text-align: center; }
            .tr7nn-hero-title { word-break: break-word; }
        }