/* =========================================
   1. 局部子导航 (Sticky Subnav)
   ========================================= */
.local-subnav {
    position: sticky;
    top: 44px; /* 紧贴全局导航栏下方 */
    width: 100%;
    background: rgba(251, 251, 253, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid #d2d2d7;
    z-index: 1000;
    transition: background 0.3s;
}

.subnav-container {
    max-width: 980px;
    margin: 0 auto;
    padding: 0 22px;
    height: 52px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.subnav-title {
    font-size: 21px;
    font-weight: 600;
    color: #1d1d1f;
    margin: 0;
}

.subnav-links {
    list-style: none;
    display: flex;
    gap: 30px;
    margin: 0;
    padding: 0;
}

.subnav-links a {
    font-size: 12px;
    color: #424245;
    text-decoration: none;
    transition: color 0.3s;
}

.subnav-links a:hover,
.subnav-links a.active {
    color: #0071e3;
}

.btn-subnav-close {
    display: none; /* 移动端可开启 */
    font-size: 18px;
    color: #424245;
}

/* =========================================
   2. 页面首屏 (Hero)
   ========================================= */
.page-hero {
    background-color: #000;
    color: #f5f5f7;
    text-align: center;
    padding-top: 60px;
    position: relative;
    overflow: hidden;
    min-height: 85vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.hero-inner {
    z-index: 2;
    padding-bottom: 50px;
}

.hero-title {
    font-size: 80px;
    font-weight: 700;
    margin-bottom: 10px;
    background: linear-gradient(180deg, #ffffff 0%, #a1a1a6 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero-subtitle {
    font-size: 32px;
    color: #a1a1a6;
    margin-bottom: 30px;
}

.hero-scroll-down {
    font-size: 17px;
    color: #2997ff;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: transform 0.3s;
}

.hero-scroll-down:hover {
    transform: translateY(5px);
}

.hero-visual {
    width: 100%;
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: flex-start;
}

.hero-bg-img {
    max-width: 80%;
    max-height: 600px;
    object-fit: contain;
    opacity: 0.9;
}

/* =========================================
   3. 通用区块样式 (Section)
   ========================================= */
.section-container {
    max-width: 980px;
    margin: 0 auto;
    padding: 120px 22px;
}

.section-header {
    text-align: center;
    margin-bottom: 80px;
}

.section-title {
    font-size: 56px;
    font-weight: 700;
    color: #f5f5f7;
    margin-bottom: 15px;
}

.section-title.text-dark {
    color: #1d1d1f;
}

.section-desc {
    font-size: 24px;
    color: #86868b;
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.4;
}

.section-desc.text-dark {
    color: #86868b;
}

/* 深色背景区块 */
.section-dark {
    background-color: #000;
}

/* 浅色背景区块 */
.section-light {
    background-color: #fbfbfd;
}

/* =========================================
   4. Bento 栅格布局 (Bento Grid)
   ========================================= */
.bento-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}

.bento-card {
    background: #161617;
    border-radius: 28px;
    padding: 40px;
    color: #f5f5f7;
    display: flex;
    flex-direction: column;
    transition: transform 0.4s ease, box-shadow 0.4s ease;
}

.bento-card:hover {
    transform: scale(1.02);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.4);
}

/* 第一个卡片跨两列，展示大图 */
.bento-card:first-child {
    grid-column: span 2;
}

.bento-card h3 {
    font-size: 28px;
    font-weight: 600;
    margin-bottom: 12px;
}

.bento-card p {
    font-size: 17px;
    color: #a1a1a6;
    line-height: 1.5;
    margin-bottom: 30px;
}

.card-img-wrap {
    width: 100%;
    height: 300px;
    border-radius: 18px;
    overflow: hidden;
    background: #000;
}

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

.bento-card:hover .card-img-wrap img {
    transform: scale(1.05);
}

/* =========================================
   5. 浅色区块组件 (大图文)
   ========================================= */
.large-image-block {
    width: 100%;
    border-radius: 32px;
    overflow: hidden;
    margin-bottom: 60px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
}

.large-image-block img {
    width: 100%;
    height: auto;
    display: block;
}

.text-block {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.text-block h3.text-dark {
    font-size: 40px;
    font-weight: 700;
    margin-bottom: 20px;
}

.text-block p.text-dark {
    font-size: 21px;
    color: #424245;
    line-height: 1.6;
}

/* =========================================
   6. 左右图文交错 (Split Layout)
   ========================================= */
.content-split {
    display: flex;
    align-items: center;
    gap: 60px;
}

.split-text {
    flex: 1;
}

.split-text .section-title {
    text-align: left;
    font-size: 48px;
}

.split-text .section-desc {
    text-align: left;
    margin: 0 0 40px;
}

.feature-list {
    list-style: none;
    padding: 0;
}

.feature-list li {
    margin-bottom: 30px;
}

.feature-list strong {
    display: block;
    font-size: 21px;
    color: #f5f5f7;
    margin-bottom: 8px;
}

.feature-list span {
    font-size: 17px;
    color: #a1a1a6;
}

.split-visual {
    flex: 1;
    border-radius: 28px;
    overflow: hidden;
}

.split-visual img {
    width: 100%;
    height: auto;
    display: block;
}

/* =========================================
   7. 超大字引言 (Quote)
   ========================================= */
.quote-title {
    font-size: 64px;
    font-weight: 700;
    line-height: 1.1;
    color: #f5f5f7;
    margin-bottom: 60px;
    background: linear-gradient(90deg, #a1a1a6, #f5f5f7, #a1a1a6);
    background-size: 200% auto;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: shine 5s linear infinite;
}

@keyframes shine {
    to { background-position: 200% center; }
}

.future-tags {
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

.tag {
    padding: 12px 24px;
    border: 1px solid #424245;
    border-radius: 980px;
    color: #f5f5f7;
    font-size: 17px;
    transition: all 0.3s;
    cursor: default;
}

.tag:hover {
    background: #fff;
    color: #000;
    border-color: #fff;
}

/* =========================================
   8. 响应式适配 (Responsive)
   ========================================= */
@media (max-width: 980px) {
    .hero-title { font-size: 60px; }
    .hero-subtitle { font-size: 24px; }
    .section-title { font-size: 44px; }
    .quote-title { font-size: 44px; }
    .content-split { flex-direction: column; }
    .bento-card:first-child { grid-column: span 1; }
    .bento-grid { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
    .subnav-links { display: none; } /* 移动端简化子导航 */
    .btn-subnav-close { display: block; }
    .page-hero { min-height: 60vh; }
    .section-container { padding: 80px 22px; }
    .section-header { margin-bottom: 50px; }
    .bento-card { padding: 30px; }
    .hero-bg-img { max-width: 100%; }
}

/* =========================================
   9. 图片缺失视觉兜底 (Visual Fallbacks)
   ⚠️ 仅在 img[src] 为空或缺失时生效
   ========================================= */

/* Hero 主视觉兜底 - 保持黑色背景+微光感 */
.hero-bg-img:not([src]),
.hero-bg-img[src=""] {
    display: block; /* 保持占位空间 */
    visibility: hidden; /* 隐藏破损图标 */
}
.hero-visual:has(.hero-bg-img:not([src])),
.hero-visual:has(.hero-bg-img[src=""]) {
    background: radial-gradient(ellipse at 50% 30%, #1a1a1a 0%, #000 70%);
    min-height: 400px; /* 防止Hero区高度塌陷 */
}

/* Bento 卡片图片兜底 - 深灰渐变匹配 #161617 卡片底色 */
.card-img-wrap:has(img:not([src])),
.card-img-wrap:has(img[src=""]) {
    background: linear-gradient(145deg, #1c1c1e 0%, #2c2c2e 100%);
    position: relative;
}
/* 移除破损图片的缩放动画避免抖动 */
.card-img-wrap:has(img:not([src])) img,
.card-img-wrap:has(img[src=""]) img {
    visibility: hidden;
}

/* 浅色区块大图兜底 - 浅灰渐变匹配 #fbfbfd 背景 */
.large-image-block:has(img:not([src])),
.large-image-block:has(img[src=""]) {
    background: linear-gradient(180deg, #f0f0f2 0%, #e8e8ed 100%);
    min-height: 300px;
    border-radius: 32px;
}
.large-image-block:has(img:not([src])) img,
.large-image-block:has(img[src=""]) img {
    display: none;
}

/* Split 左右图文区图片兜底 - 深色渐变匹配分割布局 */
.split-visual:has(img:not([src])),
.split-visual:has(img[src=""]) {
    background: linear-gradient(135deg, #1a1a1a 0%, #2a2a2a 100%);
    min-height: 320px;
    border-radius: 28px;
}
.split-visual:has(img:not([src])) img,
.split-visual:has(img[src=""]) img {
    visibility: hidden;
}

/* 全局通用：阻止所有缺失图片显示破损图标 */
img:not([src]),
img[src=""] {
    opacity: 0;
    pointer-events: none;
}