/* Base Styling - 斑斓彩调风 (Vibrant Colorful Accent Style) */
        :root {
            --primary: #4f46e5;
            --primary-hover: #4338ca;
            --secondary: #06b6d4;
            --accent-pink: #ec4899;
            --accent-amber: #f59e0b;
            --accent-emerald: #10b981;
            --bg-light: #f8fafc;
            --bg-card: #ffffff;
            --text-dark: #0f172a;
            --text-muted: #475569;
            --border-light: #e2e8f0;
            --shadow-sm: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -2px rgba(0,0,0,0.05);
            --shadow-md: 0 10px 25px -5px rgba(0,0,0,0.08), 0 8px 10px -6px rgba(0,0,0,0.04);
            --shadow-lg: 0 20px 30px -10px rgba(79, 70, 229, 0.15);
            --radius-md: 12px;
            --radius-lg: 20px;
        }

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

        html {
            scroll-behavior: smooth;
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            background-color: var(--bg-light);
            color: var(--text-dark);
            line-height: 1.6;
        }

        body {
            overflow-x: hidden;
            background: radial-gradient(circle at 10% 20%, rgba(79, 70, 229, 0.03) 0%, transparent 40%),
                        radial-gradient(circle at 90% 80%, rgba(6, 182, 212, 0.04) 0%, transparent 40%);
        }

        .container {
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }

        section {
            padding: 80px 0;
            position: relative;
        }

        /* Typography */
        h1, h2, h3, h4 {
            color: var(--text-dark);
            font-weight: 700;
            line-height: 1.3;
        }

        h2.section-title {
            font-size: 2.2rem;
            text-align: center;
            margin-bottom: 12px;
            background: linear-gradient(135deg, #0f172a 0%, #334155 100%);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        p.section-subtitle {
            text-align: center;
            color: var(--text-muted);
            font-size: 1.05rem;
            max-width: 700px;
            margin: 0 auto 50px auto;
        }

        a {
            color: var(--primary);
            text-decoration: none;
            transition: all 0.3s ease;
        }

        /* Vibrant Accent Badges & Elements */
        .tag-badge {
            display: inline-block;
            padding: 4px 12px;
            border-radius: 999px;
            font-size: 0.85rem;
            font-weight: 600;
            margin-bottom: 12px;
        }
        .tag-blue { background: rgba(79, 70, 229, 0.1); color: var(--primary); }
        .tag-cyan { background: rgba(6, 182, 212, 0.1); color: var(--secondary); }
        .tag-pink { background: rgba(236, 72, 153, 0.1); color: var(--accent-pink); }
        .tag-amber { background: rgba(245, 158, 11, 0.1); color: var(--accent-amber); }
        .tag-emerald { background: rgba(16, 185, 129, 0.1); color: var(--accent-emerald); }

        /* Header Navigation */
        .site-header {
            position: sticky;
            top: 0;
            z-index: 1000;
            background: rgba(255, 255, 255, 0.92);
            backdrop-filter: blur(12px);
            border-bottom: 1px solid var(--border-light);
            box-shadow: var(--shadow-sm);
        }

        .header-wrapper {
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 74px;
        }

        .brand-logo {
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .ai-page-logo {
            height: 40px;
            width: auto;
            display: block;
        }

        .nav-links {
            display: flex;
            align-items: center;
            gap: 0; /* Strictly set as requested */
            list-style: none;
        }

        .nav-links li a {
            padding: 8px 14px;
            font-size: 0.92rem;
            font-weight: 500;
            color: var(--text-dark);
            border-radius: 8px;
            display: inline-block;
        }

        .nav-links li a:hover {
            color: var(--primary);
            background: rgba(79, 70, 229, 0.05);
        }

        .header-actions {
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .btn {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            padding: 10px 22px;
            border-radius: 10px;
            font-weight: 600;
            font-size: 0.95rem;
            cursor: pointer;
            border: none;
            transition: all 0.3s ease;
        }

        .btn-primary {
            background: linear-gradient(135deg, var(--primary) 0%, #6366f1 100%);
            color: #ffffff !important;
            box-shadow: 0 4px 14px rgba(79, 70, 229, 0.35);
        }

        .btn-primary:hover {
            transform: translateY(-2px);
            box-shadow: 0 6px 20px rgba(79, 70, 229, 0.45);
        }

        .btn-outline {
            background: transparent;
            border: 1px solid var(--primary);
            color: var(--primary);
        }

        .btn-outline:hover {
            background: rgba(79, 70, 229, 0.08);
        }

        .mobile-menu-toggle {
            display: none;
            font-size: 1.5rem;
            background: none;
            border: none;
            cursor: pointer;
            color: var(--text-dark);
        }

        /* Hero Section (strictly NO images allowed) */
        .hero-section {
            padding: 100px 0 80px 0;
            background: radial-gradient(circle at 50% 30%, rgba(99, 102, 241, 0.12) 0%, rgba(6, 182, 212, 0.06) 45%, transparent 70%);
            text-align: center;
            position: relative;
        }

        .hero-badge-wrap {
            margin-bottom: 20px;
        }

        .hero-title {
            font-size: 2.8rem;
            line-height: 1.25;
            margin-bottom: 20px;
            letter-spacing: -0.5px;
            color: #0f172a;
        }

        .hero-desc {
            font-size: 1.2rem;
            color: var(--text-muted);
            max-width: 800px;
            margin: 0 auto 35px auto;
            line-height: 1.7;
        }

        .hero-cta-group {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 16px;
            flex-wrap: wrap;
            margin-bottom: 50px;
        }

        .hero-cta-main {
            padding: 14px 36px;
            font-size: 1.1rem;
            border-radius: 12px;
            background: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
            color: #ffffff !important;
            box-shadow: var(--shadow-lg);
        }

        .hero-cta-main:hover {
            transform: translateY(-3px) scale(1.02);
        }

        .hero-features-grid {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 20px;
            margin-top: 40px;
        }

        .hero-stat-card {
            background: var(--bg-card);
            padding: 24px 16px;
            border-radius: var(--radius-md);
            box-shadow: var(--shadow-sm);
            border: 1px solid var(--border-light);
            position: relative;
            overflow: hidden;
        }

        .hero-stat-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 4px;
        }
        .card-c1::before { background: linear-gradient(90deg, #4f46e5, #6366f1); }
        .card-c2::before { background: linear-gradient(90deg, #06b6d4, #3b82f6); }
        .card-c3::before { background: linear-gradient(90deg, #ec4899, #f43f5e); }
        .card-c4::before { background: linear-gradient(90deg, #10b981, #059669); }

        .stat-num {
            font-size: 2rem;
            font-weight: 800;
            margin-bottom: 4px;
            color: var(--text-dark);
        }

        .stat-label {
            font-size: 0.9rem;
            color: var(--text-muted);
        }

        /* Generic Section Card Styles */
        .grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 30px; }
        .grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
        .grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

        .feature-card {
            background: var(--bg-card);
            border: 1px solid var(--border-light);
            border-radius: var(--radius-md);
            padding: 28px;
            box-shadow: var(--shadow-sm);
            transition: all 0.3s ease;
        }

        .feature-card:hover {
            transform: translateY(-5px);
            box-shadow: var(--shadow-md);
            border-color: rgba(79, 70, 229, 0.3);
        }

        .card-icon-box {
            width: 48px;
            height: 48px;
            border-radius: 10px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.4rem;
            font-weight: bold;
            margin-bottom: 18px;
        }

        /* Model Pill Clouds */
        .model-cloud {
            display: flex;
            flex-wrap: wrap;
            gap: 10px;
            justify-content: center;
            margin-top: 25px;
        }

        .model-pill {
            background: #ffffff;
            border: 1px solid #cbd5e1;
            padding: 6px 16px;
            border-radius: 20px;
            font-size: 0.9rem;
            font-weight: 500;
            color: #334155;
            box-shadow: 0 2px 4px rgba(0,0,0,0.03);
            transition: all 0.2s ease;
        }

        .model-pill:hover {
            border-color: var(--primary);
            color: var(--primary);
            transform: translateY(-2px);
        }

        /* Tables */
        .table-responsive {
            width: 100%;
            overflow-x: auto;
            background: var(--bg-card);
            border-radius: var(--radius-md);
            border: 1px solid var(--border-light);
            box-shadow: var(--shadow-sm);
        }

        .custom-table {
            width: 100%;
            border-collapse: collapse;
            text-align: left;
        }

        .custom-table th, .custom-table td {
            padding: 16px 20px;
            border-bottom: 1px solid var(--border-light);
        }

        .custom-table th {
            background: #f1f5f9;
            font-weight: 700;
            color: var(--text-dark);
        }

        .custom-table tr:last-child td {
            border-bottom: none;
        }

        .rating-badge {
            background: #fef3c7;
            color: #d97706;
            padding: 6px 14px;
            border-radius: 20px;
            font-weight: 700;
            display: inline-block;
        }

        /* Accordion FAQ */
        .faq-list {
            max-width: 900px;
            margin: 0 auto;
            display: flex;
            flex-direction: column;
            gap: 14px;
        }

        .faq-item {
            background: var(--bg-card);
            border: 1px solid var(--border-light);
            border-radius: var(--radius-md);
            overflow: hidden;
            transition: all 0.3s ease;
        }

        .faq-header {
            padding: 20px 24px;
            font-weight: 600;
            font-size: 1.05rem;
            cursor: pointer;
            display: flex;
            justify-content: space-between;
            align-items: center;
            user-select: none;
        }

        .faq-header::after {
            content: '+';
            font-size: 1.4rem;
            color: var(--primary);
            transition: transform 0.3s ease;
        }

        .faq-item.active .faq-header::after {
            content: '-';
        }

        .faq-content {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.3s ease;
            background: #fafafa;
        }

        .faq-body {
            padding: 0 24px 20px 24px;
            color: var(--text-muted);
            font-size: 0.98rem;
            line-height: 1.7;
        }

        /* Review Cards */
        .review-card {
            background: var(--bg-card);
            border-radius: var(--radius-md);
            padding: 24px;
            border: 1px solid var(--border-light);
            box-shadow: var(--shadow-sm);
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }

        .review-user {
            display: flex;
            align-items: center;
            gap: 12px;
            margin-top: 16px;
        }

        .user-avatar-placeholder {
            width: 44px;
            height: 44px;
            border-radius: 50%;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 700;
        }

        /* Media Elements Section */
        .media-showcase {
            display: flex;
            flex-wrap: wrap;
            gap: 20px;
            align-items: center;
            justify-content: center;
            margin-top: 30px;
        }

        .media-box {
            border-radius: var(--radius-md);
            overflow: hidden;
            box-shadow: var(--shadow-sm);
            border: 1px solid var(--border-light);
            background: #fff;
            padding: 8px;
        }

        /* Form Styling */
        .contact-form-card {
            background: var(--bg-card);
            border-radius: var(--radius-lg);
            padding: 40px;
            box-shadow: var(--shadow-md);
            border: 1px solid var(--border-light);
        }

        .form-group {
            margin-bottom: 20px;
        }

        .form-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: var(--text-dark);
            font-size: 0.95rem;
        }

        .form-control {
            width: 100%;
            padding: 12px 16px;
            border: 1px solid var(--border-light);
            border-radius: 8px;
            font-size: 0.98rem;
            outline: none;
            transition: border-color 0.2s ease;
            background: #fdfdfd;
        }

        .form-control:focus {
            border-color: var(--primary);
            background: #fff;
        }

        /* Footer */
        .site-footer {
            background: #0f172a;
            color: #94a3b8;
            padding: 60px 0 30px 0;
            border-top: 1px solid #1e293b;
        }

        .footer-grid {
            display: grid;
            grid-template-columns: 2fr 1fr 1fr 1.5fr;
            gap: 40px;
            margin-bottom: 40px;
        }

        .footer-col h4 {
            color: #f8fafc;
            margin-bottom: 20px;
            font-size: 1.1rem;
        }

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

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

        .footer-links a {
            color: #94a3b8;
            font-size: 0.92rem;
        }

        .footer-links a:hover {
            color: #ffffff;
        }

        .friend-links-wrap {
            padding-top: 20px;
            border-top: 1px solid #1e293b;
            margin-top: 30px;
            display: flex;
            flex-wrap: wrap;
            gap: 14px;
            font-size: 0.9rem;
        }

        .friend-links-wrap a {
            color: #64748b;
        }

        .friend-links-wrap a:hover {
            color: var(--secondary);
        }

        .copyright-bar {
            text-align: center;
            padding-top: 30px;
            border-top: 1px solid #1e293b;
            font-size: 0.88rem;
            color: #64748b;
        }

        /* Responsive Breakpoints */
        @media (max-width: 992px) {
            .hero-features-grid { grid-template-columns: repeat(2, 1fr); }
            .grid-4 { grid-template-columns: repeat(2, 1fr); }
            .grid-3 { grid-template-columns: repeat(1, 1fr); }
            .footer-grid { grid-template-columns: repeat(2, 1fr); }
        }

        @media (max-width: 768px) {
            .nav-links {
                display: none;
                position: absolute;
                top: 74px;
                left: 0;
                width: 100%;
                background: #ffffff;
                flex-direction: column;
                padding: 20px;
                box-shadow: var(--shadow-md);
                border-bottom: 1px solid var(--border-light);
            }
            .nav-links.active { display: flex; }
            .mobile-menu-toggle { display: block; }
            .hero-title { font-size: 2rem; }
            .grid-2 { grid-template-columns: 1fr; }
            .grid-4 { grid-template-columns: 1fr; }
            .hero-features-grid { grid-template-columns: 1fr; }
            .footer-grid { grid-template-columns: 1fr; }
            .contact-form-card { padding: 24px; }
        }