* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Microsoft YaHei', Arial, sans-serif;
            line-height: 1.6;
            color: #333;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        }

        .j990-container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }

        .j990-header {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 1000;
        }

        .j990-nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 15px 0;
        }

        .j990-logo {
            display: flex;
            align-items: center;
            font-size: 24px;
            font-weight: bold;
            color: #667eea;
        }

        .j990-logo img {
            height: 40px;
            margin-right: 10px;
        }

        .j990-nav-menu {
            display: flex;
            list-style: none;
            gap: 30px;
        }

        .j990-nav-link {
            text-decoration: none;
            color: #333;
            font-weight: 500;
            transition: color 0.3s ease;
            position: relative;
        }

        .j990-nav-link:hover {
            color: #667eea;
        }

        .j990-nav-link::after {
            content: '';
            position: absolute;
            bottom: -5px;
            left: 0;
            width: 0;
            height: 2px;
            background: #667eea;
            transition: width 0.3s ease;
        }

        .j990-nav-link:hover::after {
            width: 100%;
        }

        .j990-main {
            margin-top: 80px;
            padding: 60px 0;
        }

        .j990-hero-section {
            text-align: center;
            color: white;
            margin-bottom: 60px;
        }

        .j990-hero-title {
            font-size: 48px;
            font-weight: bold;
            margin-bottom: 20px;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
        }

        .j990-hero-subtitle {
            font-size: 20px;
            margin-bottom: 30px;
            opacity: 0.9;
        }

        .j990-download-section {
            background: white;
            border-radius: 20px;
            padding: 50px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.1);
            margin-bottom: 40px;
        }

        .j990-download-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 30px;
            margin-bottom: 40px;
        }

        .j990-download-card {
            background: linear-gradient(135deg, #f8f9ff 0%, #e8f0ff 100%);
            border-radius: 15px;
            padding: 30px;
            text-align: center;
            border: 2px solid transparent;
            transition: all 0.3s ease;
        }

        .j990-download-card:hover {
            transform: translateY(-5px);
            border-color: #667eea;
            box-shadow: 0 15px 40px rgba(102, 126, 234, 0.2);
        }

        .j990-platform-icon {
            font-size: 48px;
            margin-bottom: 20px;
            color: #667eea;
        }

        .j990-platform-name {
            font-size: 24px;
            font-weight: bold;
            margin-bottom: 10px;
            color: #333;
        }

        .j990-version-info {
            color: #666;
            margin-bottom: 15px;
        }

        .j990-file-size {
            color: #888;
            font-size: 14px;
            margin-bottom: 20px;
        }

        .j990-download-btn {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            padding: 15px 30px;
            border-radius: 50px;
            font-size: 16px;
            font-weight: bold;
            cursor: pointer;
            transition: all 0.3s ease;
            text-decoration: none;
            display: inline-block;
            width: 100%;
        }

        .j990-download-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 30px rgba(102, 126, 234, 0.4);
        }

        .j990-features-section {
            background: rgba(255, 255, 255, 0.95);
            border-radius: 20px;
            padding: 50px;
            margin-bottom: 40px;
        }

        .j990-features-title {
            font-size: 32px;
            text-align: center;
            margin-bottom: 40px;
            color: #333;
        }

        .j990-features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 30px;
        }

        .j990-feature-item {
            text-align: center;
            padding: 20px;
        }

        .j990-feature-icon {
            font-size: 36px;
            color: #667eea;
            margin-bottom: 15px;
        }

        .j990-feature-title {
            font-size: 18px;
            font-weight: bold;
            margin-bottom: 10px;
            color: #333;
        }

        .j990-feature-desc {
            color: #666;
            line-height: 1.6;
        }

        .j990-system-requirements {
            background: rgba(255, 255, 255, 0.95);
            border-radius: 20px;
            padding: 40px;
            margin-bottom: 40px;
        }

        .j990-requirements-title {
            font-size: 24px;
            margin-bottom: 20px;
            color: #333;
        }

        .j990-requirements-list {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 20px;
        }

        .j990-requirement-item {
            background: #f8f9ff;
            padding: 20px;
            border-radius: 10px;
            border-left: 4px solid #667eea;
        }

        .j990-requirement-platform {
            font-weight: bold;
            color: #333;
            margin-bottom: 10px;
        }

        .j990-requirement-specs {
            color: #666;
            font-size: 14px;
        }

        .j990-cta-section {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border-radius: 20px;
            padding: 50px;
            text-align: center;
            color: white;
            margin-bottom: 40px;
        }

        .j990-cta-title {
            font-size: 32px;
            margin-bottom: 20px;
        }

        .j990-cta-desc {
            font-size: 18px;
            margin-bottom: 30px;
            opacity: 0.9;
        }

        .j990-cta-btn {
            background: white;
            color: #667eea;
            border: none;
            padding: 20px 40px;
            border-radius: 50px;
            font-size: 18px;
            font-weight: bold;
            cursor: pointer;
            transition: all 0.3s ease;
            text-decoration: none;
            display: inline-block;
        }

        .j990-cta-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 15px 40px rgba(0, 0, 0, 0.2);
        }

        .j990-footer {
            background: rgba(0, 0, 0, 0.8);
            color: white;
            text-align: center;
            padding: 40px 0;
        }

        .j990-footer-content {
            margin-bottom: 20px;
        }

        .j990-footer-links {
            display: flex;
            justify-content: center;
            gap: 30px;
            margin-bottom: 20px;
        }

        .j990-footer-link {
            color: white;
            text-decoration: none;
            transition: color 0.3s ease;
        }

        .j990-footer-link:hover {
            color: #667eea;
        }

        .j990-copyright {
            opacity: 0.7;
            font-size: 14px;
        }

        @media (max-width: 768px) {
            .j990-nav-menu {
                display: none;
            }

            .j990-hero-title {
                font-size: 32px;
            }

            .j990-download-section,
            .j990-features-section,
            .j990-system-requirements,
            .j990-cta-section {
                padding: 30px 20px;
            }

            .j990-footer-links {
                flex-direction: column;
                gap: 15px;
            }
        }