/* ==========================================================================
   冒泡AI — 落地页样式
   单文件、无依赖、无外部请求（字体 / 图片 / 脚本全部本地或系统自带）。
   目录：1 令牌  2 基础  3 排版  4 按钮  5 导航  6 Hero  7 区块头
        8 案例  9 能力（深色） 10 流程  11 价格  12 下载  13 页脚
        14 动效  15 无障碍与降级
   ========================================================================== */

/* 1. 设计令牌 ------------------------------------------------------------- */
:root {
  /* 色彩：单一强调色族（与 logo.svg 同源），克制使用 */
  --ink: #0B0B0F;
  --ink-soft: #16161C;
  --body: #4B4B57;
  --hairline: rgba(11, 11, 15, .08);
  --hairline-strong: rgba(11, 11, 15, .14);
  --surface: #FFFFFF;
  --canvas: #F7F7F9;
  --accent-a: #FF5A1F;
  --accent-b: #FF2D6E;
  --accent-ink: #D2114E;
  --accent-on-dark: #FF8A5C;
  --grad: linear-gradient(115deg, var(--accent-a), var(--accent-b));

  /* 形状与阴影 */
  --radius-card: 24px;
  --radius-md: 18px;
  --radius-sm: 12px;
  --radius-pill: 999px;
  --shadow-soft: 0 1px 2px rgba(11, 11, 15, .04), 0 12px 32px -12px rgba(11, 11, 15, .12);
  --shadow-lift: 0 1px 2px rgba(11, 11, 15, .05), 0 18px 40px -14px rgba(11, 11, 15, .16);

  /* 节奏 */
  --max: 1200px;
  --gut: clamp(20px, 4vw, 32px);
  --section-y: clamp(72px, 9vw, 128px);
  --ease: cubic-bezier(.22, .61, .36, 1);
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
}

body {
  margin: 0;
  background: var(--surface);
  color: var(--body);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  font-size: 16px;
  line-height: 1.75;
  overflow-x: clip;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

h1, h2, h3, p, ul, ol, figure { margin: 0; }
ul, ol { padding: 0; list-style: none; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; }

.container {
  width: 100%;
  max-width: var(--max);
  margin-inline: auto;
  padding-inline: var(--gut);
}

/* 3. 排版 ---------------------------------------------------------------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 12px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--accent-ink);
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 2px;
  border-radius: 2px;
  background-image: var(--grad);
}

.section { padding: var(--section-y) 0; }

.section__head { max-width: 760px; margin-bottom: clamp(36px, 5vw, 64px); }

.section__title {
  margin-top: 16px;
  font-size: clamp(26px, 3.2vw, 40px);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -.015em;
  color: var(--ink);
  text-wrap: balance;
}

.section__sub {
  margin-top: 16px;
  font-size: 16px;
  line-height: 1.75;
  max-width: 62ch;
}

.note {
  margin-top: clamp(24px, 3vw, 36px);
  font-size: 13.5px;
  line-height: 1.7;
  color: rgba(75, 75, 87, .82);
  max-width: 72ch;
}

.grad-text {
  background-image: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
}

@supports not ((-webkit-background-clip: text) or (background-clip: text)) {
  .grad-text { color: var(--accent-ink); -webkit-text-fill-color: currentColor; }
}

/* 4. 按钮与链接 ---------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 24px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 600;
  line-height: 1;
  text-align: center;
  white-space: nowrap;
  cursor: pointer;
  transition: transform .18s var(--ease), box-shadow .18s var(--ease), border-color .18s var(--ease), color .18s var(--ease);
}

.btn--primary {
  background-image: var(--grad);
  color: #fff;
  box-shadow: 0 1px 2px rgba(11, 11, 15, .06), 0 10px 24px -12px rgba(255, 45, 110, .5);
}

.btn--ghost {
  background: var(--surface);
  color: var(--ink);
  border-color: var(--hairline-strong);
}

.btn--sm { padding: 10px 18px; font-size: 14px; }
.btn--block { width: 100%; }

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 2px;
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
  transition: color .18s var(--ease);
}

.link-arrow span { transition: transform .18s var(--ease); }

@media (hover: hover) {
  .btn--primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 2px 4px rgba(11, 11, 15, .06), 0 16px 32px -12px rgba(255, 45, 110, .55);
  }
  .btn--ghost:hover {
    transform: translateY(-2px);
    border-color: rgba(11, 11, 15, .24);
    box-shadow: var(--shadow-soft);
  }
  .link-arrow:hover { color: var(--accent-ink); }
  .link-arrow:hover span { transform: translateX(3px); }
}

/* 5. 导航（吸顶 + 毛玻璃 + 滚动轻微收缩） -------------------------------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, .78);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--hairline);
  transition: background-color .2s var(--ease), box-shadow .2s var(--ease);
}

.nav.is-scrolled {
  background: rgba(255, 255, 255, .9);
  box-shadow: 0 1px 2px rgba(11, 11, 15, .04);
}

.nav__inner {
  display: flex;
  align-items: center;
  gap: 14px;
  height: 72px;
  transition: height .2s var(--ease);
}

.nav.is-scrolled .nav__inner { height: 60px; }

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.brand__mark { flex: 0 0 auto; }

.brand__word {
  font-size: 17px;
  font-weight: 800;
  letter-spacing: -.01em;
  color: var(--ink);
}

.brand__ai {
  background-image: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
}

.nav__links { display: none; }

.nav__disclosure { margin-left: auto; }

.nav__summary {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  height: 40px;
  padding: 0 15px;
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-pill);
  background: var(--surface);
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
  list-style: none;
  transition: border-color .18s var(--ease), box-shadow .18s var(--ease);
}

.nav__summary::-webkit-details-marker { display: none; }

/* 极窄屏只留汉堡，但文字仍留在无障碍树里（不用 display:none） */
@media (max-width: 399px) {
  .nav__summary-text {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    border: 0;
    overflow: hidden;
    clip-path: inset(50%);
    white-space: nowrap;
  }
}

.nav__burger {
  position: relative;
  display: block;
  width: 14px;
  height: 10px;
}

.nav__burger::before,
.nav__burger::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1.5px;
  border-radius: 2px;
  background: currentColor;
}

.nav__burger::before { top: 0; }
.nav__burger::after { bottom: 0; }

.nav__panel {
  position: absolute;
  top: calc(100% + 10px);
  right: var(--gut);
  display: flex;
  flex-direction: column;
  gap: 2px;
  width: min(74vw, 260px);
  padding: 10px;
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lift);
}

.nav__panel a {
  padding: 11px 12px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 500;
  color: var(--ink);
  transition: background-color .18s var(--ease);
}

.nav__panel .btn { margin-top: 6px; }

.nav__actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 0 0 auto;
}

.nav__guide {
  display: none;
  font-size: 14.5px;
  font-weight: 500;
  color: var(--body);
  transition: color .18s var(--ease);
}

@media (hover: hover) {
  .nav__summary:hover { border-color: rgba(11, 11, 15, .24); box-shadow: var(--shadow-soft); }
  .nav__panel a:hover { background: var(--canvas); }
  .nav__guide:hover { color: var(--ink); }
}

@media (min-width: 640px) {
  .nav__guide { display: inline-flex; }
}

@media (min-width: 1024px) {
  .nav__links {
    display: flex;
    align-items: center;
    gap: 2px;
    margin-left: clamp(16px, 3vw, 40px);
    margin-right: auto;
  }

  .nav__links a {
    padding: 8px 12px;
    border-radius: 10px;
    font-size: 14.5px;
    font-weight: 500;
    color: var(--body);
    transition: color .18s var(--ease), background-color .18s var(--ease);
  }

  .nav__links a:hover { color: var(--ink); background: rgba(11, 11, 15, .04); }

  /* 导航在 1024px 才展开：这一段宽度里放 6 个入口会挤到"免费下载"，
     所以只在**够宽**（≥1200px）时显示「常见问题」——它同时还在移动菜单与页脚里，
     可发现性与抓取都不受影响。 */
  @media (max-width: 1199px) {
    .nav__links a[href="#faq"] { display: none; }
  }

  .nav__disclosure { display: none; }
}

/* 6. Hero ---------------------------------------------------------------- */
.hero { padding: clamp(48px, 6vw, 88px) 0 clamp(64px, 8vw, 104px); }

.hero__inner {
  display: grid;
  gap: clamp(44px, 6vw, 72px);
  align-items: center;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-pill);
  background: var(--surface);
  font-size: 13px;
  font-weight: 600;
  line-height: 1.4;
  color: var(--ink-soft);
}

.chip::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-image: var(--grad);
  flex: 0 0 auto;
}

.hero__h1 {
  margin-top: 22px;
  font-weight: 800;
  letter-spacing: -.02em;
  color: var(--ink);
}

.hero__copy { min-width: 0; }

.hero__brand {
  display: block;
  margin-bottom: 8px;
  font-size: clamp(17px, 2.2vw, 20px);
  font-weight: 800;
  letter-spacing: .01em;
}

/* 上限 62px：标语的 9 个字（含全角标点）必须能在 1200px 内容宽度里单行放下；
   更窄的屏幕交给 text-wrap: balance，让折行落在「换人换货，/ 不重拍。」而不是留下孤字 */
.hero__slogan {
  display: block;
  font-size: clamp(38px, 5.4vw, 62px);
  line-height: 1.08;
  letter-spacing: -.02em;
  text-wrap: balance;
}

.hero__sub {
  margin-top: 22px;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.75;
  max-width: 56ch;
}

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 16px;
  margin-top: 30px;
}

.facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 26px;
  margin-top: 34px;
  font-size: 14px;
}

.facts li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.facts li::before {
  content: "";
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--accent-b);
  flex: 0 0 auto;
}

.hero__aside {
  display: flex;
  align-items: center;
  justify-content: center;
}

/* 比例放在 .hero__frame 上：它的高度由 width + aspect-ratio 决定，
   内部视频用 grid 拉伸填满，不依赖百分比高度的解析 */
.hero__panel {
  position: relative;
  width: min(100%, 340px);
  min-width: 0;
}

/* 只做上下出血：横向不超出面板宽度，避免在窄屏产生滚动溢出
   （26px 的模糊属于 ink overflow，仍然会向两侧自然晕开，但不参与滚动尺寸） */
.hero__glow {
  position: absolute;
  inset: -14% 0 -8%;
  z-index: 0;
  border-radius: 50%;
  background: radial-gradient(58% 46% at 62% 30%, rgba(255, 90, 31, .22), rgba(255, 45, 110, .15) 46%, transparent 72%);
  filter: blur(26px);
  pointer-events: none;
}

.hero__frame {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  width: 100%;
  min-width: 0;
  aspect-ratio: 9 / 16;
  padding: 10px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-card);
  background: var(--surface);
  box-shadow: var(--shadow-soft);
}

.hero__video {
  width: 100%;
  min-width: 0;
  height: 100%;
  border-radius: var(--radius-md);
  background: var(--ink);
  object-fit: cover;
}

.hero__tag {
  position: absolute;
  left: 20px;
  bottom: 20px;
  z-index: 2;
  padding: 7px 12px;
  border-radius: var(--radius-pill);
  background: rgba(11, 11, 15, .62);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  color: #fff;
  font-size: 12px;
  font-weight: 600;
  line-height: 1.4;
  white-space: nowrap;
}

@media (min-width: 960px) {
  .hero__inner { grid-template-columns: minmax(0, 1.18fr) minmax(0, .82fr); }
  .hero__aside { justify-content: flex-end; }
  .hero__panel { width: min(100%, 360px); }
}

/* 7. 区块头（通用） ------------------------------------------------------ */
.section--dark {
  background: var(--ink);
  color: rgba(255, 255, 255, .72);
}

.section--dark .section__title { color: #fff; }
.section--dark .section__sub { color: rgba(255, 255, 255, .68); }
.section--dark .eyebrow { color: var(--accent-on-dark); }

/* 8. 客户案例 ------------------------------------------------------------ */
.case-grid {
  display: grid;
  gap: clamp(20px, 2.6vw, 28px);
  grid-template-columns: minmax(0, 1fr);
}

.card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-soft);
  transition: transform .22s var(--ease), box-shadow .22s var(--ease);
}

@media (hover: hover) {
  .card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lift); }
}

/* min-width:0 贯穿整条链路：video 自带 720px 的固有宽度（width/height 属性），
   在 grid/flex 项默认 min-width:auto 的引擎里会把轨道撑到 720 而造成横向溢出 */
.case {
  display: flex;
  flex-direction: column;
  min-width: 0;
  overflow: hidden;
}

.media {
  position: relative;
  min-width: 0;
  aspect-ratio: 9 / 16;
  background: var(--ink);
  border-bottom: 1px solid var(--hairline);
  overflow: hidden;
}

.media__video {
  width: 100%;
  min-width: 0;
  height: 100%;
  object-fit: cover;
  cursor: pointer;
}

.media__play {
  position: absolute;
  left: 50%;
  top: 50%;
  display: grid;
  place-items: center;
  width: 58px;
  height: 58px;
  padding: 0;
  transform: translate(-50%, -50%);
  border: 1px solid rgba(255, 255, 255, .34);
  border-radius: 50%;
  background: rgba(11, 11, 15, .44);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  color: #fff;
  cursor: pointer;
  transition: transform .18s var(--ease), background-color .18s var(--ease), opacity .2s var(--ease);
}

.media__play .icon { width: 22px; height: 22px; }
.media__play .icon--pause { display: none; }

.media.is-playing .media__play { opacity: 0; }
.media.is-playing .icon--play { display: none; }
.media.is-playing .icon--pause { display: block; }

@media (hover: hover) {
  .media__play:hover { background: rgba(11, 11, 15, .62); transform: translate(-50%, -50%) scale(1.06); }
  .media.is-playing:hover .media__play { opacity: 1; }
}

.media__play:focus-visible,
.media.is-playing .media__play:focus-visible { opacity: 1; }

.case__body {
  display: flex;
  flex: 1;
  flex-direction: column;
  gap: 14px;
  min-width: 0;
  padding: 22px 22px 26px;
}

/* 只有一支片子的案例：参考视频与成片是同一支时，切换按钮留着没有意义。
   （用户 2026-09-24：棚拍那个案例整个换成他给的那一支。）
   用 `visibility: hidden` 而不是 `display: none` —— 后者会把那一行的高度收掉，
   于是这张卡的标题比同排另外三张高出一截，四张卡看起来没对齐。
   hidden 同时会把它移出可点区域与无障碍树，所以不会留下一个看不见却能 Tab 到的按钮。

   ⚠ 2026-09-28 更新：棚拍那条补上了真正的参考视频，所以那篇文章上的 `data-single`
   已经去掉，这条规则**目前没有任何案例在用** —— 留着是给以后"确实只有一支片子"的案例，
   加上 `data-single` 即可（同一行注释原本就写着"哪天补上参考视频那一侧就去掉它"）。 */
.case[data-single] .seg {
  visibility: hidden;
}

.seg {
  display: inline-flex;
  align-self: flex-start;
  gap: 2px;
  padding: 3px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius-pill);
  background: var(--canvas);}

.seg__btn {
  padding: 7px 12px;
  border: 0;
  border-radius: var(--radius-pill);
  background: transparent;
  font-size: 13px;
  font-weight: 600;
  line-height: 1.5;
  white-space: nowrap;
  color: var(--body);
  cursor: pointer;
  transition: background-color .18s var(--ease), color .18s var(--ease), box-shadow .18s var(--ease);
}

.seg__btn[aria-pressed="true"] {
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 1px 2px rgba(11, 11, 15, .06);
}

.case__title {
  font-size: 19px;
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: -.01em;
  color: var(--ink);
}

.case__desc { font-size: 15px; line-height: 1.7; }

@media (min-width: 640px) {
  .case-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1100px) {
  .case-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

/* 9. 核心能力（唯一深色区块） -------------------------------------------- */
.cap-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  border: 1px solid rgba(255, 255, 255, .1);
  border-radius: var(--radius-card);
  background: rgba(255, 255, 255, .1);
  overflow: hidden;
}

.cap {
  padding: clamp(24px, 3vw, 32px);
  background: var(--ink);
  transition: background-color .2s var(--ease);
}

.cap__title {
  font-size: 17px;
  font-weight: 700;
  line-height: 1.4;
  color: #fff;
}

.cap__desc {
  margin-top: 10px;
  font-size: 14.5px;
  line-height: 1.75;
  color: rgba(255, 255, 255, .66);
}

@media (hover: hover) {
  .cap:hover { background: var(--ink-soft); }
}

@media (min-width: 640px) {
  .cap-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1000px) {
  .cap-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

/* 10. 工作流程 ----------------------------------------------------------- */
.flow {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 2.6vw, 28px);
  counter-reset: step;
}

.flow__item {
  padding: clamp(24px, 3vw, 30px);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-card);
  background: var(--surface);
  box-shadow: var(--shadow-soft);
  counter-increment: step;
}

.flow__num {
  display: block;
  margin-bottom: 12px;
  font-size: 13px;
  font-weight: 800;
  line-height: 1;
  letter-spacing: .08em;
  color: var(--accent-ink);
}

.flow__num::before { content: counter(step, decimal-leading-zero); }

.flow__title {
  font-size: 18px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--ink);
}

.flow__desc { margin-top: 10px; font-size: 15px; line-height: 1.7; }

@media (min-width: 640px) {
  .flow { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1100px) {
  .flow { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

/* 11. 价格 --------------------------------------------------------------- */
.price-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 2.6vw, 28px);
}

.price { padding: clamp(26px, 3vw, 32px); }

.price__title {
  font-size: 18px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--ink);
}

.price__desc { margin-top: 12px; font-size: 15px; line-height: 1.75; }

@media (min-width: 900px) {
  .price-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

/* 11b. 常见问题（2026-09-27 做 SEO 时加的一节） ---------------------------- */
.faq {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  max-width: 880px;
  margin-inline: auto;
}

.faq__item {
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  padding: 2px clamp(18px, 2.4vw, 26px);
  box-shadow: var(--shadow-soft);
  transition: border-color .2s var(--ease), box-shadow .2s var(--ease);
}

.faq__item[open] {
  border-color: var(--hairline-strong);
  box-shadow: var(--shadow-lift);
}

.faq__q {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 0;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--ink);
  cursor: pointer;
  list-style: none;
}

.faq__q::-webkit-details-marker { display: none; }

.faq__q::after {
  content: "+";
  flex: none;
  font-size: 22px;
  font-weight: 700;
  line-height: 1;
  color: var(--accent-ink);
  transition: transform .22s var(--ease);
}

.faq__item[open] .faq__q::after { transform: rotate(45deg); }

.faq__a {
  margin: 0 0 20px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--body);
}

/* 页脚备案号（拿到号后启用 index.html 里那段注释即可） */
.footer__icp { margin-top: 8px; font-size: 13px; }
.footer__icp a { color: inherit; opacity: .72; text-decoration: none; }
.footer__icp a:hover { text-decoration: underline; }

/* 12. 四端下载 ----------------------------------------------------------- */.dl-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 2.6vw, 28px);
}

.dl {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: clamp(26px, 3vw, 32px);
}

.dl__title {
  font-size: 18px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--ink);
}

.dl__desc { font-size: 15px; line-height: 1.75; }
.dl__notice { font-size: 12px; line-height: 1.6; color: var(--body); }

.dl .btn { margin-top: auto; }

@media (min-width: 768px) {
  .dl-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1120px) {
  .dl-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

/* 13. 页脚 --------------------------------------------------------------- */
.footer {
  padding: clamp(48px, 6vw, 72px) 0;
  border-top: 1px solid var(--hairline);
  background: var(--canvas);
}

.footer__inner {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
}

.footer__brand {
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer__line { font-size: 15px; line-height: 1.7; max-width: 48ch; }

.footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 22px;
  font-size: 14px;
}

.footer__links a { transition: color .18s var(--ease); }

@media (hover: hover) {
  .footer__links a:hover { color: var(--ink); }
}

.footer__copy {
  margin-top: 10px;
  padding-top: 18px;
  border-top: 1px solid var(--hairline);
  font-size: 13px;
  color: rgba(75, 75, 87, .8);
}

@media (min-width: 860px) {
  .footer__inner {
    grid-template-columns: minmax(0, 1fr) auto;
    column-gap: 48px;
  }

  .footer__brand { grid-area: 1 / 1; }
  .footer__line { grid-area: 2 / 1; }

  .footer__links {
    grid-area: 1 / 2 / 3 / 3;
    flex-direction: column;
    align-items: flex-end;
    gap: 10px;
  }

  .footer__copy { grid-area: 3 / 1 / 4 / 3; }
}

/* 14. 动效：单次滚动显现 ------------------------------------------------ */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(14px);
}

.js [data-reveal].is-revealed {
  opacity: 1;
  transform: none;
  transition: opacity .62s var(--ease), transform .62s var(--ease);
  transition-delay: var(--reveal-delay, 0ms);
}

/* 15. 无障碍与降级 ------------------------------------------------------ */
:focus-visible {
  outline: 2px solid var(--accent-b);
  outline-offset: 2px;
}

.section--dark :focus-visible,
.media :focus-visible { outline-color: var(--accent-on-dark); }

.skip-link {
  position: absolute;
  left: 16px;
  top: -64px;
  z-index: 100;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  background: var(--ink);
  color: #fff;
  font-size: 14px;
  transition: top .18s var(--ease);
}

.skip-link:focus { top: 12px; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    transition-duration: .01ms !important;
    transition-delay: 0ms !important;
    animation-duration: .01ms !important;
  }

  .js [data-reveal] {
    opacity: 1;
    transform: none;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .nav { background: var(--surface); }
  .nav.is-scrolled { background: var(--surface); }
  .hero__tag { background: rgba(11, 11, 15, .92); }
}

@media (forced-colors: active) {
  .card,
  .cap-grid,
  .media,
  .nav { border-color: CanvasText; }

  .media__play {
    border-color: CanvasText;
    background: Canvas;
    color: CanvasText;
  }

  .grad-text,
  .brand__ai {
    color: CanvasText;
    -webkit-text-fill-color: currentColor;
  }
}