:root {
    --bg-color: #000000;
    --card-bg: #1c1c1e;
    --text-primary: #ffffff;
    --text-secondary: #86868b;
    --accent-color: #0a84ff; /* iOS Blue */
    --glass-bg: rgba(28, 28, 30, 0.75);
    --border-radius: 18px; /* 大圆角，Apple 风格 */
    --transition-spring: cubic-bezier(0.25, 0.8, 0.25, 1); /* 更有弹性的动画 */
}

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    /* 使用系统默认字体栈，自动调用 San Francisco (Mac) 或 PingFang (iOS) */
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    -webkit-font-smoothing: antialiased; /* 让字体在 Mac 上更清晰 */
}

/* 顶部导航 - 毛玻璃效果 */
.glass-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(0, 0, 0, 0.6);
    backdrop-filter: saturate(180%) blur(20px); /* 核心：高斯模糊+饱和度提升 */
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 0.5px solid rgba(255, 255, 255, 0.1);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 24px;
}

.logo {
    font-size: 1.3rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

nav a {
    color: var(--text-secondary);
    text-decoration: none;
    margin-left: 24px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s ease;
}

nav a.active, nav a:hover {
    color: var(--text-primary);
}

/* 主内容布局 */
main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 24px;
}

.hero {
    text-align: center;
    padding: 80px 0;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin: 0 0 10px 0;
    letter-spacing: -1px;
    background: linear-gradient(135deg, #fff 0%, #a5a5a5 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent; /* 渐变文字 */
}

.hero p {
    color: var(--text-secondary);
    font-size: 1.2rem;
}

/* 视频网格 - 响应式优化 */
.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 24px;
    padding-left: 5px;
}

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 30px;
}

/* 视频卡片 - 拟物感与悬停 */
.video-card {
    position: relative;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: transform 0.4s var(--transition-spring), opacity 0.3s ease;
    will-change: transform;
}

.video-card:hover {
    transform: scale(1.03);
    z-index: 10;
}

.poster-wrapper {
    position: relative;
    border-radius: var(--border-radius);
    overflow: hidden;
    aspect-ratio: 2/3; /* 保持电影海报比例 */
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    transition: box-shadow 0.4s var(--transition-spring);
}

.video-card:hover .poster-wrapper {
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.5);
}

.video-card img.poster {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.6s ease;
}

/* 信息层 */
.card-info {
    padding-top: 12px;
    padding-left: 4px;
}

.video-card .title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* 模态框 - 全屏沉浸 */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal.show {
    opacity: 1;
}

.modal-blur-bg {
    position: absolute;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(30px); /* 极其强烈的模糊背景 */
    -webkit-backdrop-filter: blur(30px);
}

.modal-content {
    position: relative;
    z-index: 1001;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.modal-header {
    position: absolute;
    top: 20px;
    right: 20px;
    width: 90%;
    display: flex;
    justify-content: flex-end;
}

.close-btn {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    padding: 8px 20px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    backdrop-filter: blur(10px);
    transition: background 0.2s;
}

.close-btn:hover {
    background: rgba(255, 255, 255, 0.4);
}

.video-wrapper {
    width: 80%;
    max-width: 1000px;
    aspect-ratio: 16/9;
    box-shadow: 0 20px 50px rgba(0,0,0,0.6);
    border-radius: 12px;
    overflow: hidden;
    background: black;
}

/* 简单入场动画 */
.fade-in-up {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.8s var(--transition-spring) forwards;
}

.delay-1 { animation-delay: 0.1s; }

@keyframes fadeInUp {
    to { opacity: 1; transform: translateY(0); }
}