/* ---------- 全局样式与重置 ---------- */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
            background: #f5f7fb;
            color: #1e293b;
            line-height: 1.5;
            display: flex;
            flex-direction: column;
            min-height: 100vh;
        }

        /* ---------- 页眉与导航栏样式 ---------- */
        .site-header {
            background: #ffffff;
            box-shadow: 0 4px 20px rgba(0, 0, 0, 0.03), 0 1px 2px rgba(0, 0, 0, 0.05);
            position: sticky;
            top: 0;
            z-index: 100;
            border-bottom: 1px solid #e9edf2;
        }

        .header-container {
            max-width: 1280px;
            margin: 0 auto;
            padding: 0 32px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 16px;
            min-height: 70px;
        }

        /* Logo区域 */
        .logo-area {
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .logo-icon {
            background: linear-gradient(135deg, #1e40af, #3b82f6);
            width: 42px;
            height: 42px;
            border-radius: 12px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 700;
            font-size: 24px;
            color: white;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
        }

        .logo-text {
            font-size: 1.6rem;
            font-weight: 700;
            letter-spacing: -0.3px;
            background: linear-gradient(135deg, #0f2b4d, #1e4a76);
            background-clip: text;
            -webkit-background-clip: text;
            color: transparent;
        }

        /* 一级导航栏：说明书 / 组装视频 */
        .nav-tabs {
            display: flex;
            gap: 12px;
            background: #f1f5f9;
            padding: 6px;
            border-radius: 48px;
        }

        .nav-btn {
            border: none;
            background: transparent;
            padding: 8px 28px;
            font-size: 1rem;
            font-weight: 600;
            border-radius: 40px;
            cursor: pointer;
            transition: all 0.2s;
            color: #334155;
            font-family: inherit;
        }

        .nav-btn.active {
            background: white;
            color: #1e40af;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05), 0 1px 1px rgba(0, 0, 0, 0.02);
        }

        .nav-btn:hover:not(.active) {
            background: #e6edf4;
            color: #0f3b6f;
        }

        /* ---------- 主体内容区 ---------- */
        .main-content {
            flex: 1;
            max-width: 1280px;
            margin: 40px auto;
            padding: 0 32px;
            width: 100%;
        }

        /* 选项卡面板切换 */
        .tab-pane {
            display: none;
            animation: fadeIn 0.25s ease-out;
        }

        .tab-pane.active-pane {
            display: block;
        }

        @keyframes fadeIn {
            from {
                opacity: 0;
                transform: translateY(6px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        /* 区域头部：标题 + 计数徽章 */
        .section-header {
            margin-bottom: 28px;
            display: flex;
            align-items: baseline;
            justify-content: space-between;
            flex-wrap: wrap;
            gap: 12px;
            border-bottom: 2px solid #e2e8f0;
            padding-bottom: 12px;
        }

        .section-header h2 {
            font-size: 1.8rem;
            font-weight: 600;
            letter-spacing: -0.2px;
            background: linear-gradient(120deg, #0f2b4d, #2c5282);
            background-clip: text;
            -webkit-background-clip: text;
            color: transparent;
        }

        .badge-count {
            background: #eef2ff;
            padding: 4px 12px;
            border-radius: 40px;
            font-size: 0.85rem;
            font-weight: 500;
            color: #1e40af;
        }

        /* 产品卡片网格布局 */
        .products-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
            gap: 24px;
            margin-top: 12px;
        }

        /* 单个产品卡片 */
        .product-card {
            background: white;
            border-radius: 24px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.02), 0 2px 6px rgba(0, 0, 0, 0.05);
            transition: transform 0.2s, box-shadow 0.2s;
            overflow: hidden;
            border: 1px solid #edf2f7;
            display: flex;
            flex-direction: column;
        }

        .product-card:hover {
            transform: translateY(-4px);
            box-shadow: 0 20px 25px -12px rgba(0, 0, 0, 0.1);
            border-color: #cbd5e1;
        }

        .card-header {
            padding: 20px 20px 8px 20px;
            display: flex;
            align-items: center;
            gap: 12px;
            border-bottom: 1px solid #f0f2f5;
        }

        .model-badge {
            background: #eef2ff;
            border-radius: 60px;
            padding: 4px 14px;
            font-weight: 700;
            font-size: 0.85rem;
            color: #1e40af;
            letter-spacing: 0.3px;
        }

        .model-name {
            font-weight: 700;
            font-size: 1.25rem;
            color: #0f172a;
        }

        .card-body {
            padding: 18px 20px 22px 20px;
            flex: 1;
        }

        /* 资源列表（说明书 / 视频项） */
        .resource-list {
            list-style: none;
            margin: 0;
            padding: 0;
            display: flex;
            flex-direction: column;
            gap: 14px;
        }

        .resource-item {
            display: flex;
            align-items: center;
            gap: 12px;
            background: #fafcff;
            border-radius: 16px;
            padding: 8px 12px;
            transition: background 0.15s;
            border: 1px solid #f0f4f9;
        }

        .resource-item:hover {
            background: #f8fafc;
            border-color: #dce3ec;
        }

        .resource-icon {
            font-size: 1.6rem;
            width: 36px;
            text-align: center;
        }

        .resource-info {
            flex: 1;
        }

        .resource-title {
            font-weight: 600;
            font-size: 0.95rem;
            color: #1e293b;
            margin-bottom: 4px;
        }

        .resource-meta {
            font-size: 0.7rem;
            color: #5b6e8c;
            display: flex;
            gap: 12px;
        }

        /* 按钮样式：打开说明书 / 观看视频 */
        .btn-link {
            background: none;
            border: none;
            color: #2563eb;
            font-weight: 500;
            font-size: 0.8rem;
            cursor: pointer;
            text-decoration: none;
            display: inline-flex;
            align-items: center;
            gap: 6px;
            padding: 6px 12px;
            border-radius: 30px;
            transition: background 0.15s;
        }

        .btn-link:hover {
            background: #eef2ff;
            text-decoration: underline;
        }

        /* 空状态提示 */
        .empty-message {
            background: #f9fbfd;
            border-radius: 28px;
            padding: 48px 24px;
            text-align: center;
            color: #5b6e8c;
            font-size: 1rem;
            border: 1px dashed #cbd5e1;
        }

        /* 页脚 */
        .site-footer {
            background: #ffffff;
            border-top: 1px solid #e9edf2;
            padding: 24px 32px;
            text-align: center;
            color: #5c6f87;
            font-size: 0.85rem;
            margin-top: 20px;
        }

        /* 响应式调整 */
        @media (max-width: 720px) {
            .header-container {
                flex-direction: column;
                align-items: stretch;
                padding: 16px 20px;
            }
            .nav-tabs {
                align-self: center;
            }
            .main-content {
                padding: 0 20px;
            }
            .products-grid {
                grid-template-columns: 1fr;
            }
            .section-header h2 {
                font-size: 1.5rem;
            }
        }

        /* ---------- 本地视频弹窗（HTML5 Video 播放器） ---------- */
        .video-modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.88);
            align-items: center;
            justify-content: center;
            z-index: 1000;
            backdrop-filter: blur(5px);
        }
        .video-modal.active {
            display: flex;
        }
        .modal-content {
            background: #0f172a;
            border-radius: 28px;
            width: 90%;
            max-width: 1000px;
            overflow: hidden;
            box-shadow: 0 25px 40px rgba(0,0,0,0.4);
            position: relative;
        }
        .modal-video-container {
            background: #000;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .modal-video-container video {
            width: 100%;
            max-height: 80vh;
            display: block;
            outline: none;
        }
        .close-modal {
            position: absolute;
            top: 12px;
            right: 18px;
            background: rgba(0,0,0,0.7);
            color: white;
            font-size: 28px;
            border: none;
            border-radius: 50%;
            width: 38px;
            height: 38px;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: 0.1s;
            z-index: 10;
            font-weight: bold;
        }
        .close-modal:hover {
            background: #dc2626;
            transform: scale(1.02);
        }
        @media (max-width: 640px) {
            .modal-content {
                width: 95%;
            }
        }