/* Custom styles */
        html {
            scroll-behavior: smooth;
        }
        body {
            font-family: 'Inter', 'Microsoft YaHei', 'SimHei', sans-serif;
            color: #333;
        }
        /* 导航栏初始透明，并固定在顶部 */
        .header-fixed {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            z-index: 1000;
            transition: all 0.3s ease-in-out;
            background-color: transparent; /* 初始透明 */
        }
        /* 导航栏滚动后的样式 */
        .header-scrolled {
            background-color: #FF0246; /* 主色背景 */
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
        }

        /* Banner 动画保持不变 */
        @keyframes bounceInUp {
            from { opacity: 0; transform: translate3d(0, 3000px, 0); }
            60% { opacity: 1; transform: translate3d(0, -20px, 0); }
            75% { transform: translate3d(0, 10px, 0); }
            90% { transform: translate3d(0, -5px, 0); }
            to { transform: translate3d(0, 0, 0); }
        }
        .animate-bounceInUp {
            animation: bounceInUp 1s ease-in-out;
        }
        @keyframes fadeInRight {
            from { opacity: 0; transform: translate3d(100%, 0, 0); }
            to { opacity: 1; transform: translate3d(0, 0, 0); }
        }
        .animate-fadeInRight {
            animation: fadeInRight 1s ease-out;
        }
        
        /* 向下滚动箭头 */
        .a_n {
            position: absolute;
            bottom: 30px;
            left: 50%;
            transform: translateX(-50%);
            display: block;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            border: 2px solid white;
            opacity: 0.8;
            transition: all 0.3s;
            cursor: pointer;
        }
        .a_n:hover {
            opacity: 1;
            background-color: rgba(255, 255, 255, 0.2);
        }
        .a_n::after {
            content: '';
            position: absolute;
            top: 12px;
            left: 11px;
            width: 10px;
            height: 10px;
            border-right: 2px solid white;
            border-bottom: 2px solid white;
            transform: rotate(45deg);
        }
        /* 章节图标 */
        .section-icon {
            display: flex;
            justify-content: center;
            align-items: center;
            width: 80px;
            height: 80px;
            border-radius: 50%;
            margin: 0 auto 1rem;
            font-size: 2rem;
            color: white;
        }
        /* 新下载卡片样式 - 模仿图片设计 */
        .download-card-gradient {
            background-image: linear-gradient(to right bottom, #FF0246, #FC6996); /* primary to secondary */
            clip-path: polygon(0 0, 100% 0, 100% 90%, 0% 100%); /* 底部斜切效果 */
        }