/* ==========================================================================
   WUTE 官网 — 共享设计系统 wute.css
   WUTE · 赛场影像：真实摄影、连续石墨背景、原色蓝色队标
   全站统一：设计令牌 / 导航 / 页面 Hero / 内容排版 / 卡片 / 页脚 / 工具类
   维护：改品牌色只需改本文件 :root
   ========================================================================== */

/* ===== 1. 设计令牌（全站唯一事实来源） ===== */
:root {
    /* 摄影之外的连续深色基底 */
    --bg-deep:        #0b0d10;
    --bg-surface:     #15181d;
    --bg-elevated:    #15181d;

    /* 品牌色 */
    --brand-blue:       #00489b;
    --brand-blue-text:  #7db4ff;
    --brand-red:        #d0121b;
    --brand-red-hover:  #e81e27;

    /* 文字层级 */
    --text-primary:    #f4f5f6;
    --text-secondary:  #abb1ba;
    --text-muted:      #abb1ba;
    --text-faint:      #abb1ba;
    --text-inverse:    #000000;

    /* 边框 */
    --border-subtle:   rgba(244, 245, 246, 0.16);
    --border-default:  rgba(244, 245, 246, 0.16);
    --border-strong:   rgba(244, 245, 246, 0.38);
    /* 仅菜单需要抬升的阴影 */
    --shadow-md:  0 2px 8px rgba(0, 0, 0, 0.55), 0 16px 48px rgba(0, 0, 0, 0.45);

    /* 字体 */
    --font-display: Arial, Helvetica, 'PingFang SC', 'Microsoft YaHei', sans-serif;
    --font-body:    'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
    --font-mono:    Consolas, 'SFMono-Regular', monospace;

    /* 布局 */
    --nav-height:  72px;
    --gutter:      clamp(24px, 5vw, 96px);
    --maxw:        1600px;
    --section-pad: clamp(64px, 7vw, 112px);

    --radius-sm:   3px;
    --radius-md:   6px;
}

/* ===== 2. 全局重置 ===== */
/* <picture> 不参与布局，保持原 <img> 的盒模型行为 */
picture { display: contents; }
* { margin: 0; padding: 0; box-sizing: border-box; }
/* 图片基础规则（替代原 Tailwind preflight）：防止 height 属性锁定导致图片竖向裁切 */
img { max-width: 100%; height: auto; }
html { scroll-behavior: smooth; overflow-x: hidden; color-scheme: dark; }
section[id], main[id], footer[id] { scroll-margin-top: var(--nav-height); }
body {
    font-family: var(--font-body);
    background-color: var(--bg-deep);
    color: var(--text-primary);
    font-size: 1rem;
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

/* 中文标题：字距收紧、行高压缩——原站 0.05em 在中文大字上会散 */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: 0;
    text-wrap: balance;
}

::selection { background: var(--brand-blue); color: #fff; }

/* 自定义滚动条（Chrome/Edge） */
::-webkit-scrollbar { width: 10px; }
::-webkit-scrollbar-track { background: var(--bg-deep); }
::-webkit-scrollbar-thumb { background: #1e2531; border-radius: 5px; border: 2px solid var(--bg-deep); }
::-webkit-scrollbar-thumb:hover { background: var(--brand-blue); }

/* 等宽 / 数据字体（原来声明了 JetBrains Mono 却从未加载，实际一直回落 Consolas） */
.mono { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

/* ===== 3. 统一导航栏 ===== */
.site-nav {
    position: fixed;
    top: 0; left: 0;
    width: 100%;
    height: var(--nav-height);
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
    align-items: center;
    padding: 0 max(var(--gutter), calc((100vw - var(--maxw)) / 2));
    z-index: 1000;
    background: rgba(11, 13, 16, 0.88);
    transition: background 0.5s ease, box-shadow 0.5s ease, backdrop-filter 0.5s ease;
}
/* 滚动后毛玻璃（半透明：透出底层内容） */
.site-nav.scrolled {
    background: rgba(11, 13, 16, 0.96);
    box-shadow: 0 1px 0 var(--border-subtle);
}
.nav-brand { display: flex; align-items: center; justify-self: start; text-decoration: none; }
.nav-brand img {
    height: 36px;
    width: auto;
    transition: opacity 0.3s ease;
}
.nav-brand:hover img { opacity: 0.8; }

.nav-links {
    display: flex;
    align-items: center;
    justify-self: center;
    gap: clamp(1rem, 2vw, 2rem);
    list-style: none;
    margin: 0;
}
.nav-links > li { display: flex; align-items: center; min-height: 44px; }
.nav-links > .nav-mobile-join { display: none; }
.nav-links a {
    display: inline-flex;
    align-items: center;
    min-height: 44px;
    color: var(--text-primary);
    text-decoration: none;
    font-size: 0.94rem;
    font-weight: 600;
    letter-spacing: 0;
    padding: 0;
    position: relative;
    transition: color 0.35s ease;
    white-space: nowrap;
}
/* 细微下划线 */
.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px; left: 0;
    width: 100%;
    height: 1px;
    background: var(--text-primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.35s ease;
}
.nav-links a:hover { color: #fff; }
.nav-links a:hover::after,
.nav-links a.active::after { transform: scaleX(1); }
.nav-links a.active { color: #fff; }

/* ===== 导航下拉菜单（技术组别 / 历年赛车） ===== */
.nav-drop { position: relative; display: flex; align-items: center; }
.nav-drop > .nav-drop-toggle { padding-right: 0; }
/* 箭头由独立按钮承担，主链接保持正常导航 */
.nav-drop > .nav-drop-toggle::before {
    display: none;
}
.nav-drop-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-left: 0.25rem;
    width: 44px;
    height: 44px;
    border: 0;
    background: none;
    color: var(--text-secondary);
    font: inherit;
    line-height: 1;
    cursor: pointer;
    transition: color 0.2s ease, transform 0.2s ease;
}
.nav-drop-button:hover,
.nav-drop-button[aria-expanded="true"] { color: var(--text-primary); }
.nav-drop-button[aria-expanded="true"] { transform: rotate(180deg); }

.drop-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(6px);
    min-width: 168px;
    /* 跟随导航栏：同透明度、同模糊（滚动后导航为 rgba(0,0,0,0.72)） */
    background: rgba(0, 0, 0, 0.72);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 4px;
    padding: 8px;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.25s ease, transform 0.25s ease, visibility 0.25s;
    z-index: 1200;
}
.nav-drop:hover > .drop-menu,
.nav-drop.open > .drop-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}
.drop-menu a {
    display: block;
    padding: 9px 16px;
    color: var(--text-secondary) !important;
    font-size: 0.88rem !important;
    letter-spacing: 0;
    text-transform: none !important;
    border-radius: 2px;
    transition: all 0.25s ease;
    white-space: nowrap;
}
.drop-menu a:hover {
    color: #fff !important;
    background: rgba(255, 255, 255, 0.08);
}
.drop-menu a::after { display: none; }

.nav-right { display: flex; align-items: center; justify-self: end; gap: 1rem; }

.nav-cta {
    padding: 0.5rem 1.5rem;
    font-size: 0.94rem;
}

/* 汉堡菜单（移动端） */
.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 44px; height: 44px;
    background: none;
    border: none;
    cursor: pointer;
    z-index: 1001;
    padding: 8px;
}
.hamburger span {
    display: block;
    width: 24px; height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: transform 0.3s ease, opacity 0.3s ease;
    transform-origin: center;
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ===== 4. 二级页面 Hero（统一模板） ===== */
.page-hero {
    position: relative;
    padding: calc(var(--nav-height) + 72px) max(var(--gutter), calc((100vw - var(--maxw)) / 2)) 64px;
    text-align: left;
    overflow: hidden;
    background-color: var(--bg-deep);
    border-bottom: 1px solid var(--border-subtle);
}
.page-hero .kicker {
    display: block;
    font-family: var(--font-body);
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    letter-spacing: 0;
    margin-bottom: 24px;
}
.page-hero h1 {
    font-size: clamp(3rem, 4.5vw, 4rem);
    font-weight: 700;
    line-height: 1.15;
    margin-bottom: 16px;
    color: var(--text-primary);
}
.page-hero .sub {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 720px;
    margin: 0;
    line-height: 1.75;
}
.page-hero .hero-line { display: none; }
.page-hero .hero-meta {
    margin-top: 16px;
    font-size: 0.875rem;
    color: var(--text-muted);
}
/* 白底 logo 盒（赞助商页用） */
.page-hero .logo-box {
    position: relative;
    z-index: 1;
    display: inline-block;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 4px;
    padding: 24px 32px;
    margin-bottom: 24px;
}
.page-hero .logo-box img { max-width: 260px; max-height: 100px; object-fit: contain; }

/* ===== 5. 通用板块标题 ===== */
.section { padding: var(--section-pad) var(--gutter); background: transparent; }
.section-label {
    display: block;
    text-align: left;
    font-family: var(--font-body);
    font-size: 0.875rem;
    font-weight: 600;
    letter-spacing: 0;
    color: var(--text-secondary);
    margin-bottom: 16px;
}
.section-title {
    font-size: clamp(2.25rem, 3vw, 2.75rem);
    font-weight: 700;
    text-align: left;
    color: var(--text-primary);
    margin-bottom: 40px;
}
.section-subtitle {
    text-align: left;
    font-size: 1rem;
    color: var(--text-secondary);
    margin-top: -24px;
    margin-bottom: 40px;
}

/* ===== 6. 内容排版（二级页正文） ===== */
.content { width: min(calc(100% - var(--gutter) * 2), var(--maxw)); max-width: none; margin: 0 auto; padding: 64px 0 112px; }
.content > p, .content > ul, .content > ol, .content > h2, .content > h3, .content > .faq, .content > .back-link { max-width: 720px; }
.content h2 {
    font-size: clamp(1.75rem, 2.5vw, 2rem);
    margin: 64px 0 24px;
    color: #fff;
    font-weight: 700;
}
.content h2:first-child { margin-top: 0; }
.content p { color: var(--text-secondary); font-size: clamp(1rem, 1.25vw, 1.125rem); margin-bottom: 1.1rem; line-height: 1.75; }
.content p strong { color: #fff; font-weight: 600; }
.content ul { padding-left: 1.5rem; margin-bottom: 1.5rem; }
.content li { color: var(--text-secondary); font-size: 0.95rem; margin-bottom: 0.5rem; line-height: 1.75; }
.content li::marker { color: var(--brand-blue-text); }
.content li strong { color: #fff; font-weight: 600; }

/* 毛玻璃卡片 */
.glass-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: 4px;
    padding: 2.5rem;
    color: var(--text-primary);
    transition: border-color 0.2s ease;
}
.glass-card:hover { border-color: var(--border-strong); }
.glass-card img { border-radius: var(--radius-sm); }
.glass-card p { color: var(--text-secondary); font-size: 0.95rem; line-height: 1.8; letter-spacing: 0.03em; }

/* 通用卡片网格 */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
    gap: 24px;
    max-width: var(--maxw);
    margin: 32px 0 0;
}
.card {
    position: relative;
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: 4px;
    padding: 32px;
    transition: border-color 0.2s ease;
}
.card:hover {
    border-color: var(--border-strong);
}
.card h3 { font-size: 1.15rem; color: #fff; letter-spacing: 0; margin-bottom: 0.75rem; }
.card p { color: var(--text-secondary); font-size: 0.92rem; line-height: 1.85; }
.card .card-num {
    display: none;
}
/* 卡片顶部配图（赞助回报等卡片用） */
.card-img-top {
    display: block;
    width: 100%;
    aspect-ratio: 16 / 9;
    object-fit: cover;
    border-radius: 6px;
    margin: -0.25rem 0 1.1rem;
    border: 1px solid var(--border-default);
    cursor: zoom-in;
    transition: filter 0.3s ease, transform 0.3s ease;
}
.card-img-top:hover { filter: brightness(1.12); }

/* 全站图片灯箱（卡片图点击放大，wute.js 动态创建） */
.lightbox {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 2000;
    background: rgba(0, 0, 0, 0.97);
    align-items: center;
    justify-content: center;
    cursor: zoom-out;
}
.lightbox.on { display: flex; }
.lightbox img { max-width: 95vw; max-height: 95vh; object-fit: contain; }
.lightbox .x {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    color: #fff;
    font-size: 1.8rem;
    line-height: 1;
    cursor: pointer;
    background: none;
    border: none;
    opacity: 0.7;
    transition: opacity 0.3s;
    z-index: 1;
}
.lightbox .x:hover { opacity: 1; }

/* 按钮 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    position: relative;
    min-height: 48px;
    padding: 0.75rem 1.5rem;
    border-radius: 2px;
    font-family: var(--font-body);
    font-size: 0.94rem;
    font-weight: 600;
    text-decoration: none;
    border: none;
    cursor: pointer;
    overflow: hidden;
    transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}
.btn-primary { background: var(--text-primary); color: var(--bg-deep); }
.btn-primary:hover { background: #dce5ef; color: var(--bg-deep); }
.btn-ghost {
    background: transparent;
    color: rgba(255, 255, 255, 0.85);
    border: 1px solid var(--border-strong);
}
.btn-ghost:hover { border-color: var(--text-primary); color: #fff; }
.btn-red { background: var(--brand-red); color: #fff; }
.btn-red:hover { background: var(--brand-red-hover); }
.btn-row { display: flex; flex-wrap: wrap; gap: 1rem; justify-content: center; margin-top: 2.5rem; }

/* 返回链接 */
.back-link {
    display: block;
    text-align: center;
    padding: 2.5rem 5%;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.88rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    border-top: 1px solid var(--border-default);
    transition: color 0.35s ease;
}
.back-link:hover { color: #fff; }

/* ===== 7. 数据条（荣誉/技术页） ===== */
.stat-strip {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2.5rem 4.5rem;
    padding: 3.5rem var(--gutter);
    border-top: 1px solid var(--border-subtle);
    border-bottom: 1px solid var(--border-subtle);
    background: transparent;
}
.stat-item { text-align: center; position: relative; }
.stat-item .stat-value {
    display: block;
    font-family: var(--font-display);
    font-size: clamp(2.4rem, 5.2vw, 3.9rem);
    font-weight: 700;
    font-variant-numeric: tabular-nums;
    color: #fff;
    letter-spacing: -0.035em;
    line-height: 1;
}
.stat-item .stat-unit {
    display: block;
    font-family: var(--font-mono);
    font-size: 0.90rem;
    color: var(--text-muted);
    margin-top: 0.85rem;
    letter-spacing: 0.22em;
    text-transform: uppercase;
    font-weight: 500;
}
.stat-item::after {
    content: '';
    position: absolute;
    right: -2.25rem; top: 50%;
    transform: translateY(-50%);
    height: 36px; width: 1px;
    background: linear-gradient(to bottom, transparent, var(--border-strong) 32%, var(--border-strong) 68%, transparent);
}
.stat-item:last-child::after { display: none; }
@media (max-width: 768px) {
    .stat-strip { gap: 2rem; }
    .stat-item::after { display: none; }
}

/* ===== 8. 时间轴（荣誉/历史页） ===== */
.timeline {
    position: relative;
    max-width: 720px;
    margin: 0;
    padding-left: 32px;
}
.timeline::before {
    content: '';
    position: absolute;
    left: 0; top: 0; bottom: 0;
    width: 1px;
    background: linear-gradient(to bottom,
        transparent 0%,
        rgba(255, 255, 255, 0.12) 3%,
        rgba(255, 255, 255, 0.12) 97%,
        transparent 100%);
}
.timeline-node { position: relative; margin-bottom: 40px; padding-left: 16px; }
.timeline-node::before {
    content: '';
    position: absolute;
    left: -2.25rem; top: 0.3rem;
    width: 8px; height: 8px;
    border-radius: 50%;
    background: var(--text-primary);
}
.timeline-year {
    font-family: var(--font-mono);
    font-size: 1.8rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    line-height: 1;
}
.timeline-title { font-size: 1.125rem; font-weight: 700; color: var(--text-primary); margin-bottom: 0.4rem; }
.timeline-desc { font-size: 0.92rem; color: var(--text-muted); line-height: 1.75; letter-spacing: 0.03em; }
.timeline-desc .tag {
    display: inline-block;
    color: #fff;
    font-size: 0.86rem;
    letter-spacing: 0.08em;
    border: 1px solid var(--border-default);
    background: var(--bg-surface);
    border-radius: 2px;
    padding: 0.15rem 0.8rem;
    margin: 0.2rem 0.35rem 0.2rem 0;
}

/* ===== 9. 技术规格表（E03 页） ===== */
.spec-table {
    width: 100%;
    max-width: 900px;
    border-collapse: collapse;
    margin: 2rem 0 1rem;
}
.spec-table tr { border-bottom: 1px solid var(--border-default); }
.spec-table tr:last-child { border-bottom: none; }
.spec-table td { padding: 1.05rem 1.25rem; vertical-align: top; }
.spec-table td:first-child {
    width: 40%;
    color: var(--text-muted);
    font-size: 0.94rem;
    font-weight: 500;
}
.spec-table td:last-child { color: #fff; font-size: 0.95rem; line-height: 1.8; }
.spec-table td:last-child .mono { color: var(--brand-blue-text); font-weight: 600; }
.spec-note {
    text-align: center;
    font-size: 0.86rem;
    color: var(--text-muted);
    letter-spacing: 0.08em;
    margin-top: 1.5rem;
}

/* ===== 10. 流程步骤（招新页） ===== */
.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 232px), 1fr));
    gap: 1.5rem;
    max-width: 1000px;
    margin: 32px 0 0;
    counter-reset: step;
}
.step {
    position: relative;
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: 4px;
    padding: 2.2rem 1.75rem 1.75rem;
    transition: border-color 0.2s ease;
}
.step:hover { border-color: var(--border-strong); }
.step::before {
    counter-increment: step;
    content: '0' counter(step);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--text-secondary);
    position: absolute;
    top: 1.1rem; right: 1.4rem;
}
.step h3 { font-size: 1rem; color: #fff; letter-spacing: 0.05em; margin-bottom: 0.6rem; }
.step p { color: var(--text-secondary); font-size: 1rem; line-height: 1.75; }

/* ===== 11. 合作伙伴：深色章节，原色 Logo 各自置于白色面板 ===== */
.sponsors { padding: var(--section-pad) var(--gutter); background: var(--bg-surface); }
.sponsors > .section-label, .sponsors > h2 { width: min(100%, var(--maxw)); margin-inline: auto; text-align: center; }
.sponsors h2 { color: var(--text-primary); font-size: clamp(2.25rem, 3vw, 2.75rem); font-weight: 700; margin-bottom: 48px; }
.case-section { max-width: var(--maxw); margin: 0 auto 64px; }
.case-title { color: var(--text-primary); font-size: 1.5rem; font-weight: 700; margin-bottom: 8px; }
.case-sub { color: var(--text-secondary); font-size: 1rem; margin-bottom: 24px; }
.case-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.case-card--featured { grid-column: auto; }
.case-card { display: flex; flex-direction: column; align-items: stretch; gap: 24px; min-width: 0; padding: 24px; text-decoration: none; background: var(--bg-deep); border: 1px solid var(--border-default); border-radius: 4px; transition: border-color .2s ease; }
.case-card:hover { border-color: var(--border-strong); }
.case-logo { display: flex; align-items: center; justify-content: center; height: 100px; padding: 16px; background: #fff; border-radius: 2px; }
.case-logo img { max-width: 100%; max-height: 70px; object-fit: contain; }
.case-body h3 { color: var(--text-primary); font-size: 1.125rem; margin-bottom: 12px; }
.case-body p { color: var(--text-secondary); font-size: .94rem; line-height: 1.75; }
.case-more { display: inline-block; margin-top: 16px; color: var(--brand-blue-text); font-size: .94rem; }
.case-footer { margin-top: 24px; }
.case-link { display: inline-flex; align-items: center; min-height: 44px; color: var(--text-primary); text-decoration: underline; text-underline-offset: 6px; }
.case-link:hover { color: var(--brand-blue-text); }
.sponsor-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 210px), 1fr)); gap: 16px; align-items: stretch; max-width: var(--maxw); margin: 0 auto; }
.sponsor-cat { grid-column: 1 / -1; margin: 32px 0 0; color: var(--text-primary); font-size: 1.125rem; font-weight: 700; }
.sponsor-cat:first-child { margin-top: 0; }
.sponsor-row { grid-column: 1 / -1; display: flex; flex-wrap: wrap; gap: 16px; }
.sponsor-item, .sponsor-title-card { display: flex; align-items: center; justify-content: center; width: 100%; height: 116px; padding: 16px; background: #fff; border: 1px solid #fff; border-radius: 2px; text-decoration: none; transition: border-color .2s ease; }
.sponsor-title-card { grid-column: 1 / -1; max-width: 480px; height: 150px; }
.sponsor-row .sponsor-item { flex: 0 1 210px; }
.sponsor-item.key-sponsor { width: 280px; height: 140px; flex-basis: 280px; }
.sponsor-item img, .sponsor-title-card img { max-width: 100%; max-height: 100%; width: auto; height: auto; object-fit: contain; }
.sponsor-item:hover, .sponsor-title-card:hover { border-color: var(--brand-blue-text); }
.sponsor-item.no-link { cursor: default; }
@media (max-width: 900px) { .case-grid { grid-template-columns: 1fr; } }
@media (max-width: 767px) { .sponsor-row .sponsor-item, .sponsor-item.key-sponsor { flex: 1 1 calc(50% - 8px); width: auto; height: 90px; } .sponsor-title-card { height: 120px; } }

/* ===== 12. 页脚（全站统一） ===== */
.site-footer {
    background: var(--bg-deep);
    border-top: 1px solid var(--border-default);
    padding: 64px var(--gutter) 0;
}
.footer-grid {
    max-width: var(--maxw);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1.6fr 1fr 1fr 1.4fr;
    gap: 48px;
    padding-bottom: 64px;
}
.footer-brand img { height: 36px; width: auto; margin-bottom: 1.1rem; }
.footer-brand p { font-size: 0.88rem; color: var(--text-muted); line-height: 1.9; max-width: 300px; }
.footer-motto {
    margin-top: 1.2rem;
    font-family: var(--font-display);
    font-size: 0.84rem;
    color: var(--text-primary);
    letter-spacing: 0;
    text-transform: uppercase;
}
.footer-col h4 {
    font-size: 0.875rem;
    color: var(--text-muted);
    letter-spacing: 0.18em;
    text-transform: uppercase;
    margin-bottom: 1.1rem;
    font-weight: 600;
}
.footer-col a {
    display: block;
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 2;
    text-decoration: none;
    transition: color 0.3s ease;
}
.footer-col a:hover { color: #fff; }
.footer-contact > div { margin-bottom: 0.9rem; }
.footer-contact label {
    display: block;
    font-size: 0.875rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.14em;
    margin-bottom: 0.2rem;
}
.footer-contact a { font-size: 0.875rem; color: var(--text-secondary); text-decoration: none; transition: color 0.3s ease; }
.footer-contact a:hover { color: #fff; }
.social-row { display: flex; flex-wrap: wrap; gap: 0.6rem; margin-top: 1.2rem; }
.social-chip {
    font-size: 0.86rem;
    color: var(--text-secondary);
    border: 1px solid var(--border-default);
    padding: 0.35rem 0.95rem;
    border-radius: 2px;
    text-decoration: none;
    transition: all 0.3s ease;
}
.social-chip:hover { color: #fff; border-color: var(--border-strong); background: var(--bg-surface); }
.footer-bottom {
    border-top: 1px solid var(--border-subtle);
    padding: 1.5rem 0 2rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem 2rem;
    justify-content: space-between;
    max-width: var(--maxw);
    margin: 0 auto;
    font-size: 0.875rem;
    color: var(--text-muted);
    letter-spacing: 0.06em;
}
.footer-bottom a { color: var(--text-muted); text-decoration: none; transition: color 0.3s ease; }
.footer-bottom a:hover { color: var(--text-secondary); }

/* ===== 13. 工具类（原 Tailwind 静态提取） ===== */
.container { width: min(calc(100% - var(--gutter) * 2), var(--maxw)); margin-inline: auto; }
.mx-auto { margin-left: auto; margin-right: auto; }
.px-6 { padding-left: 1.5rem; padding-right: 1.5rem; }
.mb-4 { margin-bottom: 1rem; }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.gap-8 { gap: 2rem; }
.w-full { width: 100%; }
.text-lg { font-size: 1.125rem; line-height: 1.75rem; }
.max-w-3xl { max-width: 48rem; }
.rounded-lg { border-radius: 0.5rem; }
.object-cover { object-fit: cover; }
.shadow-lg { box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1); }
.transition-opacity { transition-property: opacity; transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1); transition-duration: 150ms; }
.hover\:opacity-80:hover { opacity: 0.8; }
@media (min-width: 768px) {
    .md\:flex-row { flex-direction: row; }
    .md\:w-1\/2 { width: 50%; }
}

/* ===== 14. 响应式 ===== */

/* 回到顶部按钮（全站，wute.js 动态注入） */
.to-top {
    position: fixed;
    right: 2rem;
    bottom: 2rem;
    width: 46px;
    height: 46px;
    border-radius: 50%;
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
    font-size: 1.15rem;
    line-height: 1;
    cursor: pointer;
    z-index: 900;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all 0.35s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0;
}
.to-top.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}
.to-top:hover {
    border-color: var(--border-strong);
    color: #fff;
}
@media (max-width: 768px) {
    .to-top { right: 1rem; bottom: 1rem; width: 40px; height: 40px; font-size: 1rem; }
}

@media (max-width: 1024px) {
    .nav-cta { display: none; }
}
@media (max-width: 1024px) {
    :root { --nav-height: 64px; }
    .site-nav { display: flex; height: 64px; }
    .nav-brand img { height: 30px; }
    .hamburger { display: flex; }
    .nav-links {
        position: fixed;
        top: 0; left: 0;
        width: 100%;
        height: 100vh;
        height: 100dvh;
        flex-direction: column;
        justify-content: flex-start;
        align-items: stretch;
        gap: 12px;
        padding: 88px var(--gutter) 3rem;
        overflow-y: auto;
        overscroll-behavior: contain;
        -webkit-overflow-scrolling: touch;
        background: var(--bg-deep);
        transform: translateX(100%);
        visibility: hidden;
        transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1), visibility 0s linear 0.4s;
        z-index: 999;
    }
    .nav-links.open {
        transform: translateX(0);
        visibility: visible;
        transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    }
    .nav-links a { display: inline-flex; align-items: center; min-height: 44px; font-size: 1.125rem; letter-spacing: 0; }
    .nav-links > .nav-mobile-join { display: flex; border-top: 1px solid var(--border-default); margin-top: 16px; padding-top: 16px; }
    /* 移动端：下拉菜单静态展开（全屏菜单内直接列出子项） */
    .nav-drop { width: 100%; text-align: left; flex-direction: column; align-items: start; }
    .nav-drop-button { display: none; }
    .nav-drop > .nav-drop-toggle::before { display: none; }
    .nav-drop > .drop-menu {
        position: static;
        display: grid;
        grid-template-columns: repeat(2, minmax(0, 1fr));
        gap: 0 8px;
        width: 100%;
        transform: none;
        opacity: 1;
        visibility: visible;
        background: none;
        border: none;
        box-shadow: none;
        padding: 4px 0 0 16px;
        min-width: 0;
    }
    .nav-drop > .drop-menu a {
        display: flex;
        white-space: normal;
        font-size: .94rem !important;
        color: var(--text-muted) !important;
        padding: 6px 0;
        text-align: left;
        text-transform: none !important;
        letter-spacing: 0;
    }
    .nav-drop > .drop-menu a:hover {
        color: #fff !important;
        background: none;
        padding-left: 0;
    }

    .page-hero { padding: calc(var(--nav-height) + 40px) var(--gutter) 48px; }
    .page-hero h1 { font-size: clamp(2rem, 5vw, 3rem); }

    .section { padding: 64px var(--gutter); }
    .section-title { font-size: clamp(1.75rem, 4vw, 2.25rem); margin-bottom: 32px; }
    .section-subtitle { margin-top: -16px; margin-bottom: 32px; }

    .content { padding: 48px 0 64px; }
    .glass-card { padding: 1.5rem; }

    .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 32px; }
    .footer-bottom { justify-content: center; text-align: center; }
}
@media (max-width: 767px) {
    :root { --gutter: 20px; }
    .page-hero h1 { font-size: clamp(2rem, 8vw, 2.375rem); }
    .page-hero .sub { font-size: 1rem; }
    .footer-grid { grid-template-columns: 1fr; }
}

/* ===== 正文内联链接（浏览器默认蓝在深色底上不可读） ===== */
.content p a, .content li a, .card p a, .card li a {
    color: var(--brand-blue-text);
    text-decoration: none;
    border-bottom: 1px solid rgba(74, 144, 226, 0.45);
    transition: color 0.3s ease, border-bottom-color 0.3s ease;
}
.content p a:hover, .content li a:hover, .card p a:hover, .card li a:hover {
    color: #fff;
    border-bottom-color: #fff;
}
/* 合作区沿用深色页面上的可读链接色。 */
.sponsors p a, .sponsors li a { color: var(--brand-blue-text); border-bottom-color: var(--brand-blue-text); }
.sponsors p a:hover, .sponsors li a:hover { color: var(--text-primary); border-bottom-color: var(--text-primary); }

/* ===== 常见问题折叠（join 页） ===== */
.faq { max-width: 720px; margin: 0; }
.faq details {
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    background: var(--bg-surface);
    margin-bottom: 0.75rem;
    overflow: hidden;
    transition: border-color 0.3s ease;
}
.faq details:hover { border-color: rgba(255, 255, 255, 0.16); }
.faq summary {
    cursor: pointer;
    padding: 1.05rem 3rem 1.05rem 1.4rem;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    letter-spacing: 0.03em;
    list-style: none;
    position: relative;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
    content: '+';
    position: absolute;
    right: 1.35rem; top: 50%;
    transform: translateY(-50%);
    color: var(--brand-blue-text);
    font-size: 1.15rem;
    line-height: 1;
}
.faq details[open] summary::after { content: '−'; }
.faq details[open] summary { border-bottom: 1px solid var(--border-subtle); }
.faq p {
    padding: 1rem 1.4rem 1.2rem;
    color: var(--text-secondary);
    font-size: 0.85rem;
    line-height: 1.85;
    letter-spacing: 0.03em;
}

/* 工具链标签（组别页「我们用的工具」） */
.tool-tags { display: flex; flex-wrap: wrap; gap: 0.5rem; margin: 0.5rem 0 1.5rem; }
.tool-tags span {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    letter-spacing: 0.06em;
    color: var(--text-secondary);
    border: 1px solid var(--border-default);
    background: var(--bg-surface);
    border-radius: var(--radius-sm);
    padding: 0.35rem 0.7rem;
}

/* ===== 15. 可访问性补充 ===== */
.sr-only {
    position: absolute;
    width: 1px; height: 1px;
    padding: 0; margin: -1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    clip-path: inset(50%);
    white-space: nowrap;
    border: 0;
}
:focus-visible {
    outline: 2px solid var(--brand-blue-text);
    outline-offset: 4px;
}
.skip-link {
    position: fixed;
    top: 0.75rem;
    left: 0.75rem;
    z-index: 3000;
    padding: 0.7rem 1rem;
    background: var(--bg-elevated);
    color: var(--text-primary);
    transform: translateY(-150%);
}
.skip-link:focus-visible { transform: translateY(0); }
@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* ===== 16. 赛场影像视觉层：从最初版本恢复影像与交互的节奏 ===== */
:root {
    --brand-action: #0754a8;
    --brand-action-hover: #176ac4;
    --motion-ease: cubic-bezier(.22, 1, .36, 1);
}

/* 有真实影像的页面在页眉展现影像；文字所在一侧保持足够对比度。 */
.page-photo-hero .page-hero {
    min-height: clamp(370px, 38vw, 510px);
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    isolation: isolate;
    border-bottom: 0;
    background: #10141a;
}
.page-photo-hero .page-hero::before {
    content: '';
    position: absolute;
    inset: 0;
    z-index: -2;
    background-image: var(--page-hero-image);
    background-size: cover;
    background-position: var(--page-hero-position, center);
    transform: scale(1.025);
}
.page-photo-hero .page-hero::after {
    content: '';
    position: absolute;
    inset: 0;
    z-index: -1;
    background: linear-gradient(90deg, rgba(7,10,15,.9) 0%, rgba(7,10,15,.68) 43%, rgba(7,10,15,.08) 100%),
                linear-gradient(0deg, rgba(7,10,15,.66), transparent 44%);
}
.page-photo-hero .page-hero .kicker { color: #d7e2f0; }
.page-photo-hero .page-hero h1 { font-size: clamp(3rem, 5vw, 5.5rem); max-width: 900px; color: #fff; }
.page-photo-hero .page-hero .sub { color: #e1e6ec; text-wrap: pretty; }
body.page-car { --page-hero-image: url('../picture/ABC_3469-opq4142934343-hd.webp'); --page-hero-position: center 57%; }
body.page-about { --page-hero-image: url('../picture/history/赛场照片1.webp'); --page-hero-position: center 47%; }
body.page-gallery { --page-hero-image: url('../picture/gallery/2025-race/ABC_3502-opq4142956917.webp'); --page-hero-position: center 55%; }
body.page-honors { --page-hero-image: url('../picture/返回p房.webp'); --page-hero-position: center 55%; }
body.page-join { --page-hero-image: url('../picture/25大合影.webp'); --page-hero-position: center 45%; }
body.page-sponsors { --page-hero-image: url('../picture/淋雨测试.webp'); --page-hero-position: center 52%; }
body.page-album-race { --page-hero-image: url('../picture/gallery/2025-race/ABC_3502-opq4142956917.webp'); }
body.page-album-graduation { --page-hero-image: url('../picture/gallery/2026-graduation/DSC09530.webp'); }

/* 图像较少的内页保留深色页眉，靠排版和一道 WUTE 蓝线建立同一识别系统。 */
body:not(.page-photo-hero) .page-hero { min-height: 340px; }
.page-hero .kicker { text-transform: uppercase; letter-spacing: .12em; }
.page-hero .kicker::before,
.section-label::before,
.home-eyebrow::before {
    content: '';
    display: inline-block;
    width: 28px;
    height: 2px;
    margin-right: 12px;
    background: var(--brand-blue-text);
    vertical-align: .3em;
}
.page-hero h1 { letter-spacing: -.035em; }

/* 可操作的 WUTE 蓝只用于行动按钮；照片、内容与 Logo 仍承担主视觉。 */
.btn-primary, .home-page .cta-primary, .car-detail-link {
    background: var(--brand-action);
    border-color: var(--brand-action);
    color: #fff;
    transition: background .25s ease, border-color .25s ease, transform .35s var(--motion-ease);
}
.btn-primary:hover, .home-page .cta-primary:hover, .car-detail-link:hover {
    background: var(--brand-action-hover);
    border-color: var(--brand-action-hover);
    color: #fff;
    transform: translateY(-2px);
}
.nav-cta { white-space: nowrap; }
.nav-links a::after { background: var(--brand-blue-text); height: 2px; }
.home-text-link, .case-link { text-decoration-color: var(--brand-blue-text); }

/* 使长篇技术内页有清楚的阅读分节。 */
.content > h2 {
    position: relative;
    padding-top: 24px;
    border-top: 1px solid var(--border-default);
    letter-spacing: -.015em;
}
.content > h2:first-child { padding-top: 0; border-top: 0; }
.content > h2::after { content: ''; display: block; width: 38px; height: 2px; margin-top: 16px; background: var(--brand-blue-text); }
.content > h2:first-child::after { margin-top: 14px; }
.content > p, .content > ul, .content > ol { max-width: 780px; }
.content .spec-table { background: rgba(255,255,255,.018); }
.spec-table tr:hover { background: rgba(125,180,255,.055); }

/* 克制的抬升和裁切，替代所有卡片看起来完全静止的状态。 */
.card, .glass-card, .step, .case-card, .feature-card {
    transition: transform .4s var(--motion-ease), border-color .3s ease, background .3s ease;
}
.card:hover, .glass-card:hover, .step:hover, .case-card:hover { transform: translateY(-4px); border-color: rgba(125,180,255,.55); }
.feature-card:hover { transform: translateY(-3px); background: #202a37; }
.feature-card:hover span, .case-card:hover .case-more { color: #fff; }
.sponsor-item, .sponsor-title-card { transition: transform .35s var(--motion-ease), border-color .25s ease; }
.sponsor-item:not(.no-link):hover, .sponsor-title-card:hover { transform: translateY(-3px); }
.footer-motto { color: var(--brand-blue-text); }

@media (max-width: 767px) {
    .page-photo-hero .page-hero { min-height: 410px; padding-bottom: 52px; }
    .page-photo-hero .page-hero::after {
        background: linear-gradient(0deg, rgba(7,10,15,.93) 0%, rgba(7,10,15,.6) 49%, rgba(7,10,15,.22) 100%);
    }
    .page-photo-hero .page-hero h1 { font-size: clamp(2.5rem, 11vw, 3.6rem); }
    body:not(.page-photo-hero) .page-hero { min-height: 290px; }
    .content > h2 { margin-top: 52px; }
}
@media (prefers-reduced-motion: reduce) {
    .page-photo-hero .page-hero::before { transform: none; }
    .card:hover, .glass-card:hover, .step:hover, .case-card:hover,
    .feature-card:hover, .sponsor-item:hover, .sponsor-title-card:hover,
    .btn-primary:hover, .home-page .cta-primary:hover, .car-detail-link:hover { transform: none; }
}