/* ==========================================================================
   你好关键帧 · 前台设计系统 v2
   设计原则：大留白 / 中性色为主 / 单一主色 / 统一圆角 / 轻阴影 / 克制动效
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. 设计令牌 (Design Tokens)
   -------------------------------------------------------------------------- */
:root {
  /* 中性色阶 */
  --ink-950: #0a0a0b;
  --ink-900: #18181b;
  --ink-800: #27272a;
  --ink-700: #3f3f46;
  --ink-600: #52525b;
  --ink-500: #71717a;
  --ink-400: #a1a1aa;
  --ink-300: #d4d4d8;

  --line: #e8e8ec;
  --line-soft: #f1f1f4;

  --bg: #fafafa;
  --bg-alt: #f5f5f6;
  --surface: #ffffff;

  /* 单一主色（品牌橙） */
  --brand: #ff6b00;
  --brand-deep: #e85f00;
  --brand-soft: #fff5ed;
  --brand-line: #ffdcc0;

  /* 圆角 */
  --r-xs: 8px;
  --r-sm: 10px;
  --r-md: 14px;
  --r-lg: 20px;
  --r-xl: 28px;
  --r-full: 999px;

  /* 阴影（极轻） */
  --sh-1: 0 1px 2px rgba(24, 24, 27, 0.04), 0 1px 3px rgba(24, 24, 27, 0.05);
  --sh-2: 0 10px 28px -14px rgba(24, 24, 27, 0.18), 0 2px 6px rgba(24, 24, 27, 0.04);
  --sh-3: 0 28px 56px -28px rgba(24, 24, 27, 0.28);
  --sh-brand: 0 10px 24px -12px rgba(255, 107, 0, 0.45);

  /* 尺寸 */
  --container: 1200px;
  --gutter: 24px;
  --header-h: 68px;

  /* 动效 */
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-soft: cubic-bezier(0.4, 0, 0.2, 1);
  --dur: 0.5s;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", Roboto, Helvetica,
    Arial, sans-serif;
  --font-num: "SF Pro Display", -apple-system, "Segoe UI", Inter, Roboto,
    Helvetica, Arial, sans-serif;
}

/* --------------------------------------------------------------------------
   2. 基础重置
   -------------------------------------------------------------------------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.65;
  color: var(--ink-900);
  background: var(--bg);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img {
  max-width: 100%;
  display: block;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font: inherit;
  color: inherit;
  border: 0;
  background: none;
  cursor: pointer;
}

input,
textarea,
select {
  font: inherit;
  color: inherit;
}

h1,
h2,
h3,
h4,
p {
  margin: 0;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

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

:focus-visible {
  outline: 2px solid var(--brand);
  outline-offset: 3px;
  border-radius: 4px;
}

/* --------------------------------------------------------------------------
   3. 布局容器与栅格
   -------------------------------------------------------------------------- */
.shell {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 24px;
}

.section {
  padding: 88px 0;
}

.section--tight {
  padding: 64px 0;
}

.hairline {
  height: 1px;
  background: var(--line);
  border: 0;
  margin: 0;
}

/* --------------------------------------------------------------------------
   4. 排版
   -------------------------------------------------------------------------- */
.display {
  font-size: clamp(2.4rem, 5.6vw, 4rem);
  line-height: 1.06;
  letter-spacing: -0.035em;
  font-weight: 800;
  color: var(--ink-950);
}

.h-section {
  font-size: clamp(1.5rem, 2.6vw, 2.125rem);
  line-height: 1.2;
  letter-spacing: -0.025em;
  font-weight: 700;
  color: var(--ink-950);
}

.h-card {
  font-size: 1.0625rem;
  line-height: 1.45;
  font-weight: 650;
  letter-spacing: -0.01em;
  color: var(--ink-900);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-500);
}

.eyebrow::before {
  content: "";
  width: 18px;
  height: 1px;
  background: var(--ink-300);
}

.lede {
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--ink-500);
}

.muted {
  color: var(--ink-500);
}

.tiny {
  font-size: 0.8125rem;
  color: var(--ink-500);
}

.accent {
  color: var(--brand);
}

.num {
  font-family: var(--font-num);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.03em;
}

/* --------------------------------------------------------------------------
   5. 按钮 / 徽标 / 药丸
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 46px;
  padding: 0 22px;
  border-radius: var(--r-full);
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.005em;
  white-space: nowrap;
  transition: transform 0.28s var(--ease), background 0.2s var(--ease-soft),
    box-shadow 0.28s var(--ease), border-color 0.2s var(--ease-soft),
    color 0.2s var(--ease-soft);
}

.btn svg {
  flex: none;
}

.btn:active {
  transform: scale(0.975);
}

.btn--primary {
  background: var(--ink-950);
  color: #fff;
  box-shadow: var(--sh-1);
}

.btn--primary:hover {
  background: var(--brand);
  box-shadow: var(--sh-brand);
  transform: translateY(-1px);
}

.btn--brand {
  background: var(--brand);
  color: #fff;
  box-shadow: var(--sh-brand);
}

.btn--brand:hover {
  background: var(--brand-deep);
  transform: translateY(-1px);
}

.btn--ghost {
  background: var(--surface);
  color: var(--ink-800);
  border: 1px solid var(--line);
}

.btn--ghost:hover {
  border-color: var(--ink-300);
  background: #fff;
  transform: translateY(-1px);
  box-shadow: var(--sh-1);
}

.btn--sm {
  height: 38px;
  padding: 0 16px;
  font-size: 0.875rem;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 32px;
  padding: 0 14px;
  border-radius: var(--r-full);
  background: var(--surface);
  border: 1px solid var(--line);
  font-size: 0.8125rem;
  font-weight: 550;
  color: var(--ink-600);
}

.pill--brand {
  background: var(--brand-soft);
  border-color: var(--brand-line);
  color: var(--brand-deep);
}

/* 筛选 chip 组 */
.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chip {
  height: 36px;
  padding: 0 16px;
  border-radius: var(--r-full);
  border: 1px solid var(--line);
  background: var(--surface);
  font-size: 0.875rem;
  font-weight: 550;
  color: var(--ink-600);
  transition: all 0.22s var(--ease-soft);
}

.chip:hover {
  color: var(--ink-900);
  border-color: var(--ink-300);
}

.chip.is-active {
  background: var(--ink-950);
  border-color: var(--ink-950);
  color: #fff;
}

/* 分段控制器（排序） */
.segment {
  display: inline-flex;
  padding: 3px;
  border-radius: var(--r-full);
  background: var(--bg-alt);
  border: 1px solid var(--line);
}

.segment button {
  height: 32px;
  padding: 0 14px;
  border-radius: var(--r-full);
  font-size: 0.8125rem;
  font-weight: 550;
  color: var(--ink-500);
  transition: all 0.22s var(--ease-soft);
}

.segment button.is-active {
  background: var(--surface);
  color: var(--ink-900);
  box-shadow: var(--sh-1);
}

/* --------------------------------------------------------------------------
   6. 顶部导航
   -------------------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: rgba(250, 250, 250, 0.82);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s var(--ease-soft), background 0.3s var(--ease-soft);
}

.site-header.is-stuck {
  border-bottom-color: var(--line);
  background: rgba(250, 250, 250, 0.94);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 20px;
  height: var(--header-h);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: none;
  cursor: pointer;
}

.brand img {
  height: 32px;
  width: auto;
}

.brand__text {
  display: none;
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

/* 主导航 */
.nav {
  position: relative;
  display: flex;
  align-items: center;
  gap: 2px;
  margin-left: 12px;
  padding: 4px;
  border-radius: var(--r-full);
  background: var(--bg-alt);
  border: 1px solid var(--line-soft);
}

.nav__glider {
  position: absolute;
  top: 4px;
  left: 4px;
  height: calc(100% - 8px);
  border-radius: var(--r-full);
  background: var(--surface);
  box-shadow: var(--sh-1);
  transition: transform 0.46s var(--ease), width 0.46s var(--ease),
    opacity 0.3s linear;
  opacity: 0;
  pointer-events: none;
}

.nav__glider.is-ready {
  opacity: 1;
}

.nav__item {
  position: relative;
  z-index: 1;
  height: 34px;
  padding: 0 16px;
  border-radius: var(--r-full);
  font-size: 0.875rem;
  font-weight: 550;
  color: var(--ink-500);
  transition: color 0.24s var(--ease-soft);
}

.nav__item:hover {
  color: var(--ink-900);
}

.nav__item.is-active {
  color: var(--ink-950);
  font-weight: 650;
}

/* 右侧社交 */
.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 36px;
  padding: 0 13px;
  border-radius: var(--r-full);
  border: 1px solid var(--line);
  background: var(--surface);
  font-size: 0.8125rem;
  font-weight: 550;
  color: var(--ink-600);
  transition: all 0.24s var(--ease-soft);
}

.social-link:hover {
  color: var(--ink-950);
  border-color: var(--ink-300);
  transform: translateY(-1px);
  box-shadow: var(--sh-1);
}

.social-link svg {
  opacity: 0.85;
}

.social-icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--r-full);
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink-600);
  transition: all 0.24s var(--ease-soft);
}

.social-icon-btn:hover {
  color: var(--ink-950);
  border-color: var(--ink-300);
  transform: translateY(-1px);
  box-shadow: var(--sh-1);
}

.burger {
  display: none;
  width: 40px;
  height: 40px;
  border-radius: var(--r-sm);
  border: 1px solid var(--line);
  background: var(--surface);
  padding: 11px 10px;
  flex-direction: column;
  justify-content: space-between;
}

.burger span {
  display: block;
  height: 1.8px;
  border-radius: 2px;
  background: var(--ink-800);
  transition: transform 0.34s var(--ease), opacity 0.24s linear;
}

.burger.is-open span:nth-child(1) {
  transform: translateY(7.6px) rotate(45deg);
}

.burger.is-open span:nth-child(2) {
  opacity: 0;
}

.burger.is-open span:nth-child(3) {
  transform: translateY(-7.6px) rotate(-45deg);
}

/* 移动端抽屉 */
.drawer {
  position: fixed;
  inset: var(--header-h) 0 0;
  z-index: 79;
  background: var(--bg);
  padding: 20px var(--gutter) 40px;
  overflow-y: auto;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-10px);
  transition: opacity 0.3s var(--ease-soft), transform 0.4s var(--ease),
    visibility 0.3s;
}

.drawer.is-open {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.drawer__group-title {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-400);
  margin: 4px 0 12px;
}

.drawer__item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: 16px 18px;
  margin-bottom: 8px;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--surface);
  font-size: 1rem;
  font-weight: 600;
  color: var(--ink-800);
  transition: all 0.22s var(--ease-soft);
}

.drawer__item.is-active {
  border-color: var(--brand-line);
  background: var(--brand-soft);
  color: var(--brand-deep);
}

.drawer__item small {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--ink-400);
}

/* --------------------------------------------------------------------------
   7. 视图切换
   -------------------------------------------------------------------------- */
.view {
  display: none;
}

.view.is-active {
  display: block;
  animation: viewIn 0.55s var(--ease) both;
}

@keyframes viewIn {
  from {
    opacity: 0;
    transform: translateY(14px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

/* --------------------------------------------------------------------------
   8. Hero
   -------------------------------------------------------------------------- */
.hero {
  padding: 72px 0 76px;
}

.hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  gap: 56px;
  align-items: center;
}

.hero__title {
  margin: 20px 0 0;
}

.hero__title .accent {
  position: relative;
  display: inline-block;
}

.hero__desc {
  margin-top: 20px;
  max-width: 30em;
  font-size: 1.0625rem;
  color: var(--ink-500);
  line-height: 1.75;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
}

/* Hero 精选视频卡 */
.feature {
  position: relative;
  display: block;
  border-radius: var(--r-lg);
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--sh-2);
  overflow: hidden;
  transition: transform 0.5s var(--ease), box-shadow 0.5s var(--ease);
  will-change: transform;
}

.feature:hover {
  box-shadow: var(--sh-3);
}

.feature__media {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  background: var(--bg-alt);
}

.feature__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.7s var(--ease);
}

.feature:hover .feature__media img {
  transform: scale(1.045);
}

.feature__play {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: linear-gradient(180deg, rgba(9, 9, 11, 0.05), rgba(9, 9, 11, 0.42));
  opacity: 0;
  transition: opacity 0.35s var(--ease-soft);
}

.feature:hover .feature__play {
  opacity: 1;
}

.feature__play span {
  display: grid;
  place-items: center;
  width: 58px;
  height: 58px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.94);
  color: var(--ink-950);
  transform: scale(0.86);
  transition: transform 0.4s var(--ease);
}

.feature:hover .feature__play span {
  transform: scale(1);
}

.feature__tag {
  position: absolute;
  top: 14px;
  left: 14px;
  height: 28px;
  padding: 0 12px;
  display: inline-flex;
  align-items: center;
  border-radius: var(--r-full);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(6px);
  font-size: 0.75rem;
  font-weight: 650;
  color: var(--ink-900);
}

.feature__quality {
  position: absolute;
  top: 14px;
  right: 14px;
  height: 28px;
  padding: 0 11px;
  display: inline-flex;
  align-items: center;
  border-radius: var(--r-xs);
  background: rgba(9, 9, 11, 0.72);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.04em;
}

.feature__body {
  padding: 18px 20px 20px;
}

.feature__title {
  margin-top: 10px;
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink-900);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* --------------------------------------------------------------------------
   9. 数据统计
   -------------------------------------------------------------------------- */
.stats {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.stat {
  padding: 34px 28px;
  border-left: 1px solid var(--line);
}

.stat:first-child {
  border-left: 0;
  padding-left: 0;
}

.stat__value {
  display: flex;
  align-items: baseline;
  gap: 3px;
  font-size: clamp(2rem, 3.4vw, 2.75rem);
  font-weight: 800;
  line-height: 1;
  color: var(--ink-950);
}

.stat__unit {
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--brand);
}

.stat__label {
  margin-top: 10px;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--ink-800);
}

.stat__sub {
  margin-top: 3px;
  font-size: 0.8125rem;
  color: var(--ink-400);
}

/* 后台开关「显示数据卡小字说明」关闭时，隐藏下方说明文字 */
.stats.is-no-sub .stat__sub {
  display: none;
}

/* --------------------------------------------------------------------------
   10. 区块标题
   -------------------------------------------------------------------------- */
.section-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  margin-bottom: 32px;
}

.section-head__desc {
  margin-top: 12px;
  max-width: 46em;
  font-size: 1rem;
  color: var(--ink-500);
}

.section-head__tools {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

/* --------------------------------------------------------------------------
   11. 视频网格
   -------------------------------------------------------------------------- */
.video-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 26px 24px;
}

.video-card {
  display: block;
  border-radius: var(--r-md);
  transition: transform 0.42s var(--ease);
}

.video-card:hover {
  transform: translateY(-4px);
}

.video-card__media {
  position: relative;
  aspect-ratio: 16 / 9;
  border-radius: var(--r-md);
  overflow: hidden;
  background: var(--bg-alt);
  border: 1px solid var(--line);
}

.video-card__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.65s var(--ease);
}

.video-card:hover .video-card__media img {
  transform: scale(1.05);
}

.video-card__play {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: rgba(9, 9, 11, 0.28);
  opacity: 0;
  transition: opacity 0.3s var(--ease-soft);
}

.video-card:hover .video-card__play {
  opacity: 1;
}

.video-card__play span {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.95);
  color: var(--ink-950);
  transform: scale(0.85);
  transition: transform 0.35s var(--ease);
}

.video-card:hover .video-card__play span {
  transform: scale(1);
}

.video-card__dur {
  position: absolute;
  right: 10px;
  bottom: 10px;
  height: 22px;
  padding: 0 8px;
  display: inline-flex;
  align-items: center;
  border-radius: 6px;
  background: rgba(9, 9, 11, 0.76);
  color: #fff;
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.video-card__cat {
  position: absolute;
  left: 10px;
  top: 10px;
  height: 24px;
  padding: 0 10px;
  display: inline-flex;
  align-items: center;
  border-radius: var(--r-full);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(6px);
  font-size: 0.6875rem;
  font-weight: 650;
  color: var(--ink-900);
}

.video-card__title {
  margin-top: 14px;
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink-900);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  transition: color 0.2s linear;
}

.video-card:hover .video-card__title {
  color: var(--brand-deep);
}

.video-card__desc {
  margin-top: 6px;
  font-size: 0.8125rem;
  line-height: 1.6;
  color: var(--ink-500);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-card__meta {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-top: 10px;
  font-size: 0.75rem;
  color: var(--ink-400);
}

.video-card__meta span {
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

/* 空状态 */
.empty {
  grid-column: 1 / -1;
  padding: 64px 24px;
  text-align: center;
  border: 1px dashed var(--line);
  border-radius: var(--r-lg);
  background: var(--surface);
  color: var(--ink-400);
}

.empty svg {
  margin: 0 auto 14px;
  opacity: 0.5;
}

.empty strong {
  display: block;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--ink-600);
}

.empty span {
  font-size: 0.8125rem;
}

/* --------------------------------------------------------------------------
   12. 合作品牌跑马灯
   -------------------------------------------------------------------------- */
.partners {
  padding: 56px 0 0;
}

.marquee {
  position: relative;
  /* 上下各留 12px 缓冲：卡片悬停时会 translateY(-3px) 上浮并投出阴影，
     而这里为了裁掉横向滚动溢出必须用 overflow:hidden。
     不留缓冲的话，上浮的顶部和向下的阴影会被容器上下边缘切掉。
     ⚠️ 只加纵向 padding，不加横向 —— app.js 用 clientWidth 算「一组卡片要铺多宽」，
     横向 padding 会把这个计算带偏。margin-top 30 → 18，视觉间距保持不变。 */
  margin-top: 18px;
  padding: 12px 0;
  overflow: hidden;
  -webkit-mask-image: linear-gradient(
    90deg,
    transparent,
    #000 9%,
    #000 91%,
    transparent
  );
  mask-image: linear-gradient(90deg, transparent, #000 9%, #000 91%, transparent);
}

.marquee__track {
  display: flex;
  align-items: center;
  width: max-content;
  animation: marquee 46s linear infinite;
}

.marquee:hover .marquee__track {
  animation-play-state: paused;
}

@keyframes marquee {
  from {
    transform: translate3d(0, 0, 0);
  }
  to {
    transform: translate3d(-50%, 0, 0);
  }
}

.partner {
  flex: none;
  display: grid;
  place-items: center;
  width: 176px;
  height: 92px;
  margin-right: 18px;
  padding: 18px 20px;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--surface);
  transition: border-color 0.3s var(--ease-soft), box-shadow 0.3s var(--ease),
    transform 0.3s var(--ease);
}

.partner:hover {
  border-color: var(--ink-300);
  box-shadow: var(--sh-2);
  transform: translateY(-3px);
}

.partner img {
  max-width: 118px;
  max-height: 42px;
  width: auto;
  height: auto;
  object-fit: contain;
  filter: grayscale(1);
  opacity: 0.62;
  transition: filter 0.35s var(--ease-soft), opacity 0.35s var(--ease-soft),
    transform 0.35s var(--ease);
}

.partner:hover img {
  filter: grayscale(0);
  opacity: 1;
  transform: scale(1.04);
}

.partner__monogram {
  font-size: 0.9375rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: var(--ink-400);
}

/* --------------------------------------------------------------------------
   13. 页面通用头部（内页 Banner）
   -------------------------------------------------------------------------- */
.page-head {
  padding: 64px 0 40px;
}

.page-head__title {
  margin-top: 18px;
  font-size: clamp(2rem, 4.4vw, 3.25rem);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.035em;
  color: var(--ink-950);
}

.page-head__desc {
  margin-top: 18px;
  max-width: 52em;
  font-size: 1.0625rem;
  line-height: 1.75;
  color: var(--ink-500);
}

/* --------------------------------------------------------------------------
   14. 素材页
   -------------------------------------------------------------------------- */
.materials-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 40px;
  align-items: center;
  padding: 44px 0 8px;
}

.materials-hero__art {
  justify-self: end;
  width: 100%;
  max-width: 300px;
}

.filter-bar {
  position: sticky;
  top: var(--header-h);
  z-index: 30;
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  padding: 16px 0;
  margin-bottom: 8px;
  background: linear-gradient(180deg, var(--bg) 72%, rgba(250, 250, 250, 0));
}

.search {
  position: relative;
  margin-left: auto;
  width: 280px;
  max-width: 100%;
}

.search svg {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--ink-400);
  pointer-events: none;
}

.search input {
  width: 100%;
  height: 40px;
  padding: 0 16px 0 40px;
  border-radius: var(--r-full);
  border: 1px solid var(--line);
  background: var(--surface);
  font-size: 0.875rem;
  transition: border-color 0.2s var(--ease-soft), box-shadow 0.2s var(--ease-soft);
}

.search input::placeholder {
  color: var(--ink-400);
}

.search input:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 3px rgba(255, 107, 0, 0.12);
}

.material-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  padding-bottom: 40px;
}

.material-card {
  display: flex;
  flex-direction: column;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--surface);
  overflow: hidden;
  transition: transform 0.42s var(--ease), box-shadow 0.42s var(--ease),
    border-color 0.3s var(--ease-soft);
}

.material-card:hover {
  transform: translateY(-4px);
  border-color: var(--ink-300);
  box-shadow: var(--sh-2);
}

.material-card__media {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--bg-alt);
}

.material-card__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.65s var(--ease);
}

.material-card:hover .material-card__media img {
  transform: scale(1.05);
}

.material-card__badge {
  position: absolute;
  left: 12px;
  top: 12px;
  height: 26px;
  padding: 0 11px;
  display: inline-flex;
  align-items: center;
  border-radius: var(--r-full);
  background: rgba(255, 255, 255, 0.94);
  font-size: 0.6875rem;
  font-weight: 650;
  color: var(--ink-900);
}

.material-card__size {
  position: absolute;
  right: 12px;
  bottom: 12px;
  height: 24px;
  padding: 0 9px;
  display: inline-flex;
  align-items: center;
  border-radius: 6px;
  background: rgba(9, 9, 11, 0.72);
  color: #fff;
  font-size: 0.6875rem;
  font-weight: 600;
}

.material-card__body {
  display: flex;
  flex-direction: column;
  flex: 1;
  padding: 18px 20px 20px;
}

.material-card__title {
  font-size: 1rem;
  font-weight: 650;
  line-height: 1.5;
  letter-spacing: -0.01em;
  color: var(--ink-900);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.material-card__desc {
  margin-top: 8px;
  font-size: 0.8125rem;
  line-height: 1.65;
  color: var(--ink-500);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.material-card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 14px;
}

.material-card__foot {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px solid var(--line-soft);
}

.material-card__foot .btn {
  width: 100%;
}

/* --------------------------------------------------------------------------
   15. 加入我们
   -------------------------------------------------------------------------- */
.join-hero {
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  gap: 48px;
  align-items: stretch;
  padding: 56px 0 8px;
}

.join-hero__left {
  display: flex;
  flex-direction: column;
}

.join-hero__title {
  font-size: clamp(2.1rem, 4.6vw, 3.4rem);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -0.035em;
  color: var(--ink-950);
}

.join-hero__desc {
  margin-top: 20px;
  max-width: 40em;
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--ink-500);
}

.join-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: auto;
  padding-top: 30px;
}

.join-fact {
  flex: 1 1 150px;
  padding: 18px 20px;
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--surface);
}

.join-fact__num {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--ink-950);
}

.join-fact__label {
  margin-top: 4px;
  font-size: 0.8125rem;
  color: var(--ink-500);
}

.perks {
  display: flex;
  flex-direction: column;
  padding: 26px 26px 8px;
  border-radius: var(--r-lg);
  border: 1px solid var(--line);
  background: var(--surface);
  box-shadow: var(--sh-1);
}

.perks__title {
  flex: none;
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--ink-950);
}

.perk {
  display: flex;
  flex: 1 1 auto;
  gap: 14px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line-soft);
}

.perk:last-child {
  border-bottom: 0;
}

.perk__idx {
  flex: none;
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  border-radius: var(--r-xs);
  background: var(--brand-soft);
  color: var(--brand-deep);
  font-size: 0.75rem;
  font-weight: 700;
}

.perk strong {
  display: block;
  font-size: 0.9375rem;
  font-weight: 650;
  color: var(--ink-900);
}

.perk span {
  display: block;
  margin-top: 4px;
  font-size: 0.8125rem;
  line-height: 1.65;
  color: var(--ink-500);
}

/* 岗位列表 */
.job-list {
  display: grid;
  gap: 14px;
}

.job {
  border-radius: var(--r-md);
  border: 1px solid var(--line);
  background: var(--surface);
  overflow: hidden;
  transition: border-color 0.28s var(--ease-soft), box-shadow 0.34s var(--ease);
}

.job:hover {
  border-color: var(--ink-300);
  box-shadow: var(--sh-1);
}

.job.is-open {
  border-color: var(--ink-300);
  box-shadow: var(--sh-2);
}

.job__head {
  display: flex;
  align-items: center;
  gap: 20px;
  width: 100%;
  padding: 22px 24px;
  text-align: left;
}

.job__main {
  flex: 1;
  min-width: 0;
}

.job__title {
  font-size: 1.0625rem;
  font-weight: 650;
  letter-spacing: -0.015em;
  color: var(--ink-950);
}

.job__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  margin-top: 8px;
  font-size: 0.8125rem;
  color: var(--ink-500);
}

.job__tags span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.job__tags svg {
  color: var(--ink-300);
  flex: none;
}

.job__chev {
  flex: none;
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  border: 1px solid var(--line);
  color: var(--ink-500);
  transition: transform 0.4s var(--ease), background 0.24s var(--ease-soft),
    color 0.24s var(--ease-soft), border-color 0.24s var(--ease-soft);
}

.job.is-open .job__chev {
  transform: rotate(180deg);
  background: var(--ink-950);
  border-color: var(--ink-950);
  color: #fff;
}

.job__body {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.45s var(--ease);
}

.job.is-open .job__body {
  grid-template-rows: 1fr;
}

.job__body > div {
  overflow: hidden;
}

.job__inner {
  padding: 0 24px 26px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.job__block-title {
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-400);
  margin-bottom: 12px;
}

.job__list li {
  position: relative;
  padding-left: 18px;
  margin-bottom: 10px;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--ink-600);
}

.job__list li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 10px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--brand);
}

.job__perk {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: var(--r-sm);
  background: var(--brand-soft);
  font-size: 0.8125rem;
  font-weight: 550;
  color: var(--brand-deep);
}

.job__apply {
  margin-top: 18px;
}

/* 底部 CTA 条 */
.cta-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  flex-wrap: wrap;
  margin-top: 40px;
  padding: 32px 36px;
  border-radius: var(--r-lg);
  background: var(--ink-950);
  color: #fff;
}

.cta-bar h3 {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.cta-bar p {
  margin-top: 8px;
  max-width: 46em;
  font-size: 0.875rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.62);
}

.cta-bar .btn--brand {
  flex: none;
}

/* --------------------------------------------------------------------------
   16. 关于我们
   -------------------------------------------------------------------------- */
.about-head {
  padding: 64px 0 12px;
  max-width: 46em;
}

.about-block {
  padding: 56px 0 8px;
}

.about-block__head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  margin-bottom: 28px;
}

.team-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.member {
  border-radius: var(--r-lg);
  border: 1px solid var(--line);
  background: var(--surface);
  overflow: hidden;
  transition: transform 0.42s var(--ease), box-shadow 0.42s var(--ease),
    border-color 0.3s var(--ease-soft);
}

.member:hover {
  transform: translateY(-5px);
  border-color: var(--ink-300);
  box-shadow: var(--sh-2);
}

.member__avatar {
  position: relative;
  aspect-ratio: 1 / 1;
  background: var(--bg-alt);
  overflow: hidden;
}

.member__avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.6s var(--ease);
}

.member:hover .member__avatar img {
  transform: scale(1.05);
}

.member__quote {
  position: absolute;
  inset: auto 0 0 0;
  padding: 44px 18px 16px;
  background: linear-gradient(180deg, rgba(9, 9, 11, 0), rgba(9, 9, 11, 0.86));
  color: #fff;
  font-size: 0.8125rem;
  line-height: 1.6;
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.36s var(--ease-soft), transform 0.42s var(--ease);
}

.member:hover .member__quote {
  opacity: 1;
  transform: none;
}

.member__body {
  padding: 18px 20px 22px;
}

.member__name {
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--ink-950);
}

.member__role {
  margin-top: 5px;
  font-size: 0.8125rem;
  font-weight: 550;
  color: var(--brand-deep);
}

.member__major {
  margin-top: 8px;
  font-size: 0.75rem;
  color: var(--ink-400);
}

.member__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 14px;
}

.member__tags span {
  padding: 4px 10px;
  border-radius: var(--r-full);
  background: var(--bg-alt);
  font-size: 0.6875rem;
  font-weight: 550;
  color: var(--ink-600);
}

.member__works {
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--line-soft);
  font-size: 0.75rem;
  line-height: 1.65;
  color: var(--ink-500);
}

.member__works b {
  color: var(--ink-700);
  font-weight: 650;
}

/* 我们在做什么 */
.focus-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.focus-card {
  padding: 28px 26px;
  border-radius: var(--r-lg);
  border: 1px solid var(--line);
  background: var(--surface);
  transition: transform 0.42s var(--ease), box-shadow 0.42s var(--ease),
    border-color 0.3s var(--ease-soft);
}

.focus-card:hover {
  transform: translateY(-5px);
  border-color: var(--ink-300);
  box-shadow: var(--sh-2);
}

.focus-card__icon {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: var(--r-md);
  background: var(--brand-soft);
  color: var(--brand-deep);
}

.focus-card h3 {
  margin-top: 18px;
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -0.015em;
  color: var(--ink-950);
}

.focus-card p {
  margin-top: 8px;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--ink-500);
}

/* 合作与联系 */
.contact-band {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
  gap: 40px;
  align-items: center;
  padding: 40px;
  border-radius: var(--r-xl);
  border: 1px solid var(--line);
  background: var(--surface);
}

.contact-band__desc {
  margin-top: 16px;
  max-width: 40em;
  font-size: 1rem;
  line-height: 1.8;
  color: var(--ink-500);
}

.contact-band__side {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.contact-band__id {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line-soft);
  font-size: 0.75rem;
  color: var(--ink-400);
}

.contact-band__id b {
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--ink-900);
  letter-spacing: -0.01em;
}

.contact-band__actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.contact-band__actions .btn {
  width: 100%;
}

/* --------------------------------------------------------------------------
   17. 页脚
   -------------------------------------------------------------------------- */
.site-footer {
  margin-top: 72px;
  border-top: 1px solid var(--line);
  background: var(--surface);
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  padding: 40px 0 28px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.footer-brand img {
  height: 30px;
  width: auto;
}

.footer-brand span {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--ink-500);
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.footer-nav button {
  padding: 8px 14px;
  border-radius: var(--r-full);
  font-size: 0.875rem;
  font-weight: 550;
  color: var(--ink-500);
  transition: all 0.22s var(--ease-soft);
}

.footer-nav button:hover {
  color: var(--ink-950);
  background: var(--bg-alt);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  padding: 20px 0 32px;
  border-top: 1px solid var(--line-soft);
  font-size: 0.8125rem;
  color: var(--ink-400);
}

/* --------------------------------------------------------------------------
   18. Toast
   -------------------------------------------------------------------------- */
.toast {
  position: fixed;
  left: 50%;
  bottom: 34px;
  z-index: 200;
  transform: translate(-50%, 22px);
  display: inline-flex;
  align-items: center;
  gap: 10px;
  max-width: min(92vw, 460px);
  padding: 13px 20px;
  border-radius: var(--r-full);
  background: var(--ink-950);
  color: #fff;
  font-size: 0.875rem;
  font-weight: 550;
  box-shadow: var(--sh-3);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s var(--ease-soft), transform 0.44s var(--ease),
    visibility 0.3s;
}

.toast.is-show {
  opacity: 1;
  visibility: visible;
  transform: translate(-50%, 0);
}

.toast__dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--brand);
  flex: none;
}

/* --------------------------------------------------------------------------
   19. 动效：滚动入场
   -------------------------------------------------------------------------- */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.7s var(--ease-soft), transform 0.8s var(--ease);
  transition-delay: var(--rv-delay, 0ms);
}

.reveal.is-in {
  opacity: 1;
  transform: none;
}

/* 卡片按压缩感 */
.pressable {
  transition: transform 0.2s var(--ease);
}

.pressable.is-pressed {
  transform: scale(0.975);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  .reveal {
    opacity: 1;
    transform: none;
  }
}

/* --------------------------------------------------------------------------
   20. 响应式
   -------------------------------------------------------------------------- */
@media (max-width: 1080px) {
  .hero__grid {
    gap: 40px;
  }
  .video-grid,
  .material-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .team-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .contact-band {
    grid-template-columns: minmax(0, 1fr) minmax(0, 280px);
    gap: 32px;
    padding: 32px;
  }
}

@media (max-width: 900px) {
  :root {
    --gutter: 20px;
    --header-h: 62px;
  }

  .nav,
  .header-actions .social-link,
  .header-actions .social-icon-btn {
    display: none;
  }

  .burger {
    display: flex;
  }

  .section {
    padding: 60px 0;
  }

  .hero {
    padding: 40px 0 52px;
  }

  .hero__grid,
  .join-hero,
  .materials-hero,
  .contact-band {
    grid-template-columns: minmax(0, 1fr);
  }

  .hero__grid {
    gap: 36px;
  }

  .feature {
    max-width: 520px;
  }

  .materials-hero {
    padding-top: 20px;
  }

  .materials-hero__art {
    justify-self: start;
    max-width: 220px;
  }

  .stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .stat {
    padding: 24px 20px;
  }

  .stat:nth-child(odd) {
    border-left: 0;
    padding-left: 0;
  }

  .stat:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line);
  }

  .contact-band {
    padding: 26px 22px;
    border-radius: var(--r-lg);
  }

  .focus-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .job__inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px;
  }

  .job__head {
    padding: 18px 20px;
    gap: 14px;
  }

  .cta-bar {
    padding: 26px 24px;
  }

  .filter-bar {
    position: static;
    background: none;
    padding: 14px 0;
  }

  .search {
    margin-left: 0;
    width: 100%;
    order: 3;
  }

  .section-head {
    align-items: flex-start;
  }
}

@media (max-width: 640px) {
  .video-grid,
  .material-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  /* 团队卡在窄屏改为横向紧凑排版 */
  .team-grid {
    grid-template-columns: minmax(0, 1fr);
    gap: 12px;
  }

  .member {
    display: grid;
    grid-template-columns: 104px minmax(0, 1fr);
    align-items: stretch;
  }

  .member__avatar {
    aspect-ratio: auto;
    height: 100%;
    min-height: 104px;
    border-radius: 0;
  }

  .member__quote {
    display: none;
  }

  .member__body {
    padding: 16px 18px 18px;
  }

  .member__works {
    display: none;
  }

  .display {
    font-size: clamp(2.1rem, 9vw, 2.8rem);
  }

  .hero__actions .btn {
    flex: 1 1 auto;
  }

  .partner {
    width: 148px;
    height: 84px;
    padding: 16px;
  }

  .partner img {
    max-width: 104px;
    max-height: 38px;
  }

  .join-facts {
    gap: 10px;
  }

  .join-fact {
    flex: 1 1 45%;
  }

  .about-head,
  .page-head {
    padding-top: 40px;
  }

  .contact-band {
    padding: 22px 18px;
  }

  .footer-top,
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }

  .toast {
    bottom: 20px;
  }
}