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

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
            line-height: 1.6;
            color: #333;
            background: #f8fafc;
        }

        .j990-header {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 1000;
            border-bottom: 1px solid rgba(0, 0, 0, 0.1);
        }

        .j990-nav {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 70px;
        }

        .j990-logo img {
            height: 40px;
            width: auto;
        }

        .j990-menu-toggle {
            display: none;
            flex-direction: column;
            background: none;
            border: none;
            cursor: pointer;
            padding: 5px;
        }

        .j990-menu-toggle span {
            width: 25px;
            height: 3px;
            background: #333;
            margin: 3px 0;
            transition: 0.3s;
        }

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

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

        .j990-nav-menu a:hover,
        .j990-nav-menu a.active {
            color: #007bff;
        }

        .j990-nav-menu a.active::after {
            content: '';
            position: absolute;
            bottom: -5px;
            left: 0;
            right: 0;
            height: 2px;
            background: #007bff;
        }

        .j990-nav-overlay {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: rgba(0, 0, 0, 0.5);
            z-index: 999;
        }

        .j990-main {
            margin-top: 70px;
            min-height: calc(100vh - 70px);
        }

        .j990-hero-section {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            padding: 80px 0;
            text-align: center;
            position: relative;
            overflow: hidden;
        }

        .j990-hero-section::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: url('images/features.jpg') center/cover;
            opacity: 0.1;
            z-index: 1;
        }

        .j990-hero-content {
            max-width: 800px;
            margin: 0 auto;
            padding: 0 20px;
            position: relative;
            z-index: 2;
        }

        .j990-hero-title {
            font-size: 3rem;
            font-weight: 700;
            margin-bottom: 20px;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
        }

        .j990-hero-subtitle {
            font-size: 1.2rem;
            opacity: 0.9;
            margin-bottom: 40px;
        }

        .j990-search-box {
            max-width: 500px;
            margin: 0 auto;
            position: relative;
        }

        .j990-search-input {
            width: 100%;
            padding: 15px 50px 15px 20px;
            border: none;
            border-radius: 50px;
            font-size: 16px;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
        }

        .j990-search-btn {
            position: absolute;
            right: 5px;
            top: 50%;
            transform: translateY(-50%);
            background: #007bff;
            border: none;
            color: white;
            padding: 10px 15px;
            border-radius: 50px;
            cursor: pointer;
            transition: background 0.3s;
        }

        .j990-search-btn:hover {
            background: #0056b3;
        }

        .j990-support-nav {
            background: white;
            padding: 30px 0;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        }

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

        .j990-support-categories {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 20px;
        }

        .j990-category-card {
            background: #f8f9fa;
            padding: 20px;
            border-radius: 10px;
            text-align: center;
            cursor: pointer;
            transition: all 0.3s;
            border: 2px solid transparent;
        }

        .j990-category-card:hover,
        .j990-category-card.active {
            background: #007bff;
            color: white;
            transform: translateY(-5px);
            box-shadow: 0 10px 25px rgba(0, 123, 255, 0.3);
        }

        .j990-category-icon {
            font-size: 2rem;
            margin-bottom: 10px;
            display: block;
        }

        .j990-category-title {
            font-weight: 600;
            margin-bottom: 5px;
        }

        .j990-category-desc {
            font-size: 0.9rem;
            opacity: 0.8;
        }

        .j990-content-section {
            padding: 60px 0;
        }

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

        .j990-content-grid {
            display: grid;
            grid-template-columns: 1fr 300px;
            gap: 40px;
        }

        .j990-main-content {
            background: white;
            border-radius: 15px;
            padding: 40px;
            box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
        }

        .j990-sidebar {
            display: flex;
            flex-direction: column;
            gap: 30px;
        }

        .j990-sidebar-card {
            background: white;
            border-radius: 15px;
            padding: 25px;
            box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
        }

        .j990-sidebar-title {
            font-size: 1.2rem;
            font-weight: 600;
            margin-bottom: 20px;
            color: #333;
            border-bottom: 2px solid #007bff;
            padding-bottom: 10px;
        }

        .j990-quick-links {
            list-style: none;
        }

        .j990-quick-links li {
            margin-bottom: 10px;
        }

        .j990-quick-links a {
            color: #666;
            text-decoration: none;
            display: flex;
            align-items: center;
            padding: 8px 0;
            transition: color 0.3s;
        }

        .j990-quick-links a:hover {
            color: #007bff;
        }

        .j990-quick-links a::before {
            content: '→';
            margin-right: 10px;
            color: #007bff;
        }

        .j990-contact-info {
            text-align: center;
        }

        .j990-contact-item {
            margin-bottom: 15px;
            padding: 15px;
            background: #f8f9fa;
            border-radius: 10px;
        }

        .j990-contact-icon {
            font-size: 1.5rem;
            margin-bottom: 5px;
            display: block;
        }

        .j990-contact-text {
            font-size: 0.9rem;
            color: #666;
        }

        .j990-faq-section {
            margin-bottom: 50px;
        }

        .j990-section-title {
            font-size: 2rem;
            font-weight: 700;
            margin-bottom: 30px;
            color: #333;
            text-align: center;
        }

        .j990-faq-list {
            display: flex;
            flex-direction: column;
            gap: 20px;
        }

        .j990-faq-item {
            background: #f8f9fa;
            border-radius: 10px;
            overflow: hidden;
            transition: all 0.3s;
        }

        .j990-faq-item:hover {
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
        }

        .j990-faq-question {
            padding: 20px;
            cursor: pointer;
            display: flex;
            justify-content: space-between;
            align-items: center;
            font-weight: 600;
            background: white;
            border-bottom: 1px solid #eee;
        }

        .j990-faq-question:hover {
            background: #f8f9fa;
        }

        .j990-faq-toggle {
            font-size: 1.2rem;
            color: #007bff;
            transition: transform 0.3s;
        }

        .j990-faq-item.active .j990-faq-toggle {
            transform: rotate(45deg);
        }

        .j990-faq-answer {
            padding: 0 20px;
            max-height: 0;
            overflow: hidden;
            transition: all 0.3s;
            background: white;
        }

        .j990-faq-item.active .j990-faq-answer {
            padding: 20px;
            max-height: 500px;
        }

        .j990-install-guide {
            margin-bottom: 50px;
        }

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

        .j990-step-card {
            background: white;
            padding: 30px;
            border-radius: 15px;
            text-align: center;
            position: relative;
            box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
            transition: transform 0.3s;
        }

        .j990-step-card:hover {
            transform: translateY(-5px);
        }

        .j990-step-number {
            position: absolute;
            top: -15px;
            left: 50%;
            transform: translateX(-50%);
            background: #007bff;
            color: white;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 700;
            font-size: 1.2rem;
        }

        .j990-step-title {
            font-size: 1.3rem;
            font-weight: 600;
            margin: 20px 0 15px;
            color: #333;
        }

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

        .j990-download-section {
            background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
            padding: 60px 0;
            margin: 50px 0;
            border-radius: 20px;
            color: white;
            text-align: center;
        }

        .j990-download-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 30px;
            margin-top: 40px;
        }

        .j990-download-card {
            background: rgba(255, 255, 255, 0.1);
            backdrop-filter: blur(10px);
            padding: 30px;
            border-radius: 15px;
            transition: transform 0.3s;
        }

        .j990-download-card:hover {
            transform: translateY(-5px);
            background: rgba(255, 255, 255, 0.2);
        }

        .j990-platform-icon {
            font-size: 3rem;
            margin-bottom: 15px;
            display: block;
        }

        .j990-platform-name {
            font-size: 1.3rem;
            font-weight: 600;
            margin-bottom: 10px;
        }

        .j990-platform-info {
            font-size: 0.9rem;
            opacity: 0.9;
            margin-bottom: 20px;
        }

        .j990-download-btn {
            background: white;
            color: #007bff;
            padding: 12px 25px;
            border: none;
            border-radius: 25px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            text-decoration: none;
            display: inline-block;
        }

        .j990-download-btn:hover {
            background: #f8f9fa;
            transform: scale(1.05);
        }

        .j990-footer {
            background: #2c3e50;
            color: white;
            padding: 50px 0 30px;
            margin-top: 80px;
        }

        .j990-footer-content {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 40px;
        }

        .j990-footer-section h3 {
            font-size: 1.3rem;
            margin-bottom: 20px;
            color: #ecf0f1;
        }

        .j990-footer-section p,
        .j990-footer-section a {
            color: #bdc3c7;
            text-decoration: none;
            line-height: 1.8;
        }

        .j990-footer-section a:hover {
            color: #3498db;
        }

        .j990-footer-links {
            list-style: none;
        }

        .j990-footer-links li {
            margin-bottom: 10px;
        }

        .j990-footer-bottom {
            border-top: 1px solid #34495e;
            margin-top: 40px;
            padding-top: 20px;
            text-align: center;
            color: #95a5a6;
        }

        @media (max-width: 768px) {
            .j990-menu-toggle {
                display: flex;
            }

            .j990-nav-menu {
                display: none;
                position: fixed;
                top: 70px;
                left: 0;
                right: 0;
                background: white;
                flex-direction: column;
                padding: 20px;
                box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
                z-index: 1001;
            }

            .j990-nav-menu.active {
                display: flex;
            }

            .j990-nav-overlay.active {
                display: block;
            }

            .j990-hero-title {
                font-size: 2rem;
            }

            .j990-content-grid {
                grid-template-columns: 1fr;
            }

            .j990-sidebar {
                order: -1;
            }

            .j990-main-content {
                padding: 25px;
            }

            .j990-support-categories {
                grid-template-columns: 1fr;
            }

            .j990-steps-grid {
                grid-template-columns: 1fr;
            }

            .j990-download-grid {
                grid-template-columns: repeat(2, 1fr);
            }
        }

        @media (max-width: 480px) {
            .j990-download-grid {
                grid-template-columns: 1fr;
            }

            .j990-hero-section {
                padding: 50px 0;
            }

            .j990-main-content {
                padding: 20px;
            }
        }