/* ========== 全局样式重置 ========== */
        * {
            margin: 0;
            padding: 0; /*消除默认边距*/
            box-sizing: border-box;/*确认盒模型*/
            font-family: 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
        }

        /* 确保根元素全高，用于背景伪元素覆盖 */
        html, body {
            height: 100%;
            width: 100%;
        }

        /* 主体背景：纯黑作为底色（会透过半透明背景图） */
        body {
            background-color: #000000;
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            overflow-x: hidden;
            padding: 2rem 0;
            position: relative;      /* 为伪元素背景定位提供参考 */
        }

        /* ----- 背景图片层：80% 不透明度 ----- */
        /* 使用伪元素加载 background2.jpg，设置 opacity:0.8 实现80%不透明度，同时保留黑色底色透出 */
        body::before {
            content: '';
            position: fixed;        /* 固定视口，确保背景覆盖整个可视区域且不随滚动偏移 */
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: url('../background2.jpg') center center / cover no-repeat;
            opacity: 0.8;           /* 80% 不透明度 (0.8 = 80%不透明) */
            z-index: -2;            /* 置于最底层，黑色背景在更下方（body背景色） */
            pointer-events: none;    /* 保证所有鼠标/触摸事件直接穿透到下层元素，不影响卡片交互 */
        }

        /* 可选：为了增加视觉深度，在伪元素和内容之间不加额外干扰，卡片半透自然透出背景图 */

        /* 卡片容器：承载所有分页卡片 */
        .notebook-container {
            position: relative;
            width: 90%;
            max-width: 1200px;
            height: 700px;
            display: flex;
            align-items: center;
            overflow: visible;
        }

        /* 分页卡片：活页纸样式 (玻璃半透质感) */
        .page-card {
            position: absolute;
            width: 75%;
            max-width: 900px;
            height: 90%;
            background-color: rgba(255, 255, 255, 0.08);
            border: 2px solid rgba(255, 255, 255, 0.9);
            border-radius: 16px;
            box-shadow: 0 0 20px rgba(255, 255, 255, 0.3),
                        inset 0 0 20px rgba(255, 255, 255, 0.05);
            backdrop-filter: blur(8px);
            transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
            display: flex;
            flex-direction: column;
            padding: 2rem;
            color: #f0f0f0;
            cursor: pointer;
            overflow: hidden;
        }

        /* 左侧装订边+打孔效果 */
        .page-card::before {
            content: '';
            position: absolute;
            left: 0;
            top: 0;
            bottom: 0;
            width: 60px;
            background-color: rgba(200, 200, 200, 0.15);
            border-right: 1px solid rgba(255, 255, 255, 0.2);
        }

        /* 打孔装饰 */
        .page-card::after {
            content: '';
            position: absolute;
            left: 15px;
            top: 2rem;
            bottom: 2rem;
            width: 20px;
            background-image: radial-gradient(circle, transparent 60%, rgba(255,255,255,0.8) 60%, rgba(255,255,255,0.8) 70%, transparent 70%);
            background-size: 20px 60px;
            background-repeat: repeat-y;
        }

        /* 序号样式：大数字 */
        .page-number {
            position: absolute;
            top: 1.5rem;
            left: 80px;
            font-size: 6rem;
            font-weight: 900;
            color: rgba(255, 255, 255, 0.9);
            line-height: 1;
            z-index: 2;
            text-shadow: 0 0 4px rgba(0,0,0,0.5);
        }

        /* 视频容器 */
        .video-wrapper {
            margin-top: 8rem;
            width: 100%;
            height: 45%;
            border-radius: 8px;
            overflow: hidden;
            border: 1px solid rgba(255, 255, 255, 0.3);
            background-color: rgba(0, 0, 0, 0.5);
        }

        .video-wrapper video {
            width: 100%;
            height: 100%;
            object-fit: cover;
        }

        /* 文字介绍区域 */
        .text-content {
            margin-top: 1.5rem;
            padding: 1.5rem;
            background-color: rgba(255, 255, 255, 0.05);
            border-radius: 8px;
            flex: 1;
            overflow-y: auto;
            scrollbar-width: thin;
            scrollbar-color: rgba(255,255,255,0.4) rgba(0,0,0,0.2);
        }
        .text-content::-webkit-scrollbar {
            width: 5px;
        }
        .text-content::-webkit-scrollbar-track {
            background: rgba(0,0,0,0.2);
            border-radius: 4px;
        }
        .text-content::-webkit-scrollbar-thumb {
            background: rgba(255,255,255,0.4);
            border-radius: 4px;
        }

        .text-content h3 {
            font-size: 1.5rem;
            margin-bottom: 1rem;
            color: #ffffff;
            border-bottom: 1px solid rgba(255, 255, 255, 0.2);
            padding-bottom: 0.5rem;
        }

        .text-content p {
            font-size: 1rem;
            line-height: 1.8;
            color: #e0e0e0;
            margin-bottom: 1rem;
        }

        /* 卡片层级与位置：层层交叠 (动态js控制样式，但保留初始结构样式) */
        .page-card:nth-child(1) {
            left: 50%;
            transform: translateX(-50%) scale(1);
            z-index: 4;
            opacity: 1;
        }
        .page-card:nth-child(2) {
            left: 50%;
            transform: translateX(-35%) scale(0.95);
            z-index: 3;
            opacity: 0.8;
        }
        .page-card:nth-child(3) {
            left: 50%;
            transform: translateX(-20%) scale(0.9);
            z-index: 2;
            opacity: 0.6;
        }
        .page-card:nth-child(4) {
            left: 50%;
            transform: translateX(-5%) scale(0.85);
            z-index: 1;
            opacity: 0.4;
        }
        
        /* 左上角返回主页按钮样式 */
        #home-btn {
            position: absolute;
            top: 20px;
            left: 20px;
            z-index: 300;
            background: rgba(20, 30, 55, 0.85);
            backdrop-filter: blur(8px);
            border: 1px solid #ffaa66;
            color: #ffddbb;
            padding: 8px 20px;
            border-radius: 40px;
            cursor: pointer;
            font-size: 16px;
            font-weight: 600;
            transition: all 0.25s ease;
            font-family: inherit;
            box-shadow: 0 2px 8px rgba(0,0,0,0.3);
            letter-spacing: 1px;
        }
        #home-btn:hover {
            background: #ff884d;
            color: white;
            border-color: white;
            box-shadow: 0 0 16px rgba(255,136,77,0.6);
            transform: scale(1.02);
        }

        /* 滑动控制按钮 */
        .nav-btn {
            position: absolute;
            top: 50%;
            transform: translateY(-50%);
            width: 50px;
            height: 50px;
            border-radius: 50%;
            background-color: rgba(255, 255, 255, 0.1);
            border: 2px solid rgba(255, 255, 255, 0.8);
            color: #ffffff;
            font-size: 1.5rem;
            cursor: pointer;
            z-index: 10;
            transition: all 0.3s ease;
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .nav-btn:hover {
            background-color: rgba(255, 255, 255, 0.2);
            box-shadow: 0 0 15px rgba(255, 255, 255, 0.5);
        }

        .prev-btn {
            left: 20px;
        }

        .next-btn {
            right: 20px;
        }

        /* 响应式适配 */
        @media (max-width: 768px) {
            .page-number {
                font-size: 4rem;
            }
            .page-card {
                width: 85%;
                padding: 1.5rem;
            }
            .video-wrapper {
                margin-top: 6rem;
                height: 40%;
            }
            .text-content {
                padding: 1rem;
            }
            .nav-btn {
                width: 40px;
                height: 40px;
                font-size: 1.2rem;
            }
            #home-btn {
                top: 12px;
                left: 12px;
                padding: 6px 14px;
                font-size: 14px;
            }
        }
        
        /* 针对高度较小的设备优化卡片内部间距 */
        @media (max-height: 700px) {
            .page-card {
                height: 92%;
            }
            .video-wrapper {
                margin-top: 5rem;
                height: 40%;
            }
            .text-content {
                padding: 0.8rem;
            }
        }

        /* 小屏幕优化 (≤480px) */
        @media (max-width: 480px) {
            body {
                padding: 1rem 0;
            }
            .notebook-container {
                width: 95%;
                height: calc(100vh - 2rem);
            }
            .page-card {
                width: 92%;
                padding: 1rem;
                height: 95%;
            }
            .page-number {
                font-size: 3rem;
                left: 60px;
                top: 1rem;
            }
            .page-card::before {
                width: 45px;
            }
            .page-card::after {
                left: 10px;
                width: 15px;
                background-size: 15px 50px;
            }
            .video-wrapper {
                margin-top: 4.5rem;
                height: 38%;
            }
            .text-content {
                padding: 0.8rem;
                margin-top: 1rem;
            }
            .text-content h3 {
                font-size: 1.1rem;
            }
            .text-content p {
                font-size: 0.85rem;
                line-height: 1.6;
            }
            .nav-btn {
                width: 44px;
                height: 44px;
                font-size: 1.3rem;
            }
            .prev-btn {
                left: 5px;
            }
            .next-btn {
                right: 5px;
            }
            #home-btn {
                padding: 0.7rem 1.2rem;
                font-size: 0.9rem;
                min-height: 44px;
            }
        }

        /* 超小屏幕优化 (≤360px) */
        @media (max-width: 360px) {
            .page-card {
                width: 95%;
                padding: 0.8rem;
            }
            .page-number {
                font-size: 2.5rem;
                left: 50px;
            }
            .video-wrapper {
                margin-top: 4rem;
                height: 35%;
            }
            .text-content h3 {
                font-size: 1rem;
            }
            .text-content p {
                font-size: 0.8rem;
            }
            .nav-btn {
                width: 40px;
                height: 40px;
                font-size: 1.1rem;
            }
            #home-btn {
                top: 8px;
                left: 8px;
                padding: 0.6rem 1rem;
                font-size: 0.85rem;
            }
        }

        /* 横屏模式优化 */
        @media (max-height: 500px) and (orientation: landscape) {
            body {
                padding: 0.5rem 0;
            }
            .notebook-container {
                height: calc(100vh - 1rem);
            }
            .page-card {
                height: 95%;
                padding: 1rem;
            }
            .page-number {
                font-size: 2.5rem;
                top: 0.8rem;
            }
            .video-wrapper {
                margin-top: 3.5rem;
                height: 50%;
            }
            .text-content {
                margin-top: 0.8rem;
                padding: 0.6rem;
            }
            .text-content h3 {
                font-size: 0.95rem;
                margin-bottom: 0.6rem;
            }
            .text-content p {
                font-size: 0.75rem;
                margin-bottom: 0.5rem;
            }
            .nav-btn {
                width: 38px;
                height: 38px;
                font-size: 1rem;
            }
            #home-btn {
                padding: 0.5rem 1rem;
                font-size: 0.8rem;
            }
        }

        /* 安全区域适配（iPhone刘海屏等） */
        @supports (padding: env(safe-area-inset-bottom)) {
            body {
                padding-left: env(safe-area-inset-left);
                padding-right: env(safe-area-inset-right);
            }
            #home-btn {
                left: max(12px, env(safe-area-inset-left));
            }
        }