/* =========================================================
   GEMU-style Surface Site — 核心样式表
   1. 设计令牌 (Design Tokens)
   2. 基础重置 (Reset)
   3. 排版 (Typography)
   4. 布局容器与栅格 (Layout & Grid)
   5. 通用组件 (Buttons / Eyebrow / Divider / Card)
   6. 区块样式 (Sections)
   7. 页头 / 导航 / 移动菜单 (Header & Nav)
   8. 页脚 (Footer)
   9. 动效 (Motion)
   10. 响应式断点 (Breakpoints)
   11. 可访问性 (A11y)
   ========================================================= */

/* ---------- 1. 设计令牌 ---------- */
:root {
  /* 品牌色 —— 暖调中性 + 黄铜点缀（贴合 WPC/SPC 木塑质感） */
  --c-ink:        #14171A;   /* 主文字 / 深色底 */
  --c-ink-soft:   #2C3138;
  --c-body:       #4A5259;   /* 正文 */
  --c-muted:      #7B848C;   /* 辅助文字 */
  --c-paper:      #FFFFFF;   /* 主背景 */
  --c-paper-warm: #FAF9F5;   /* 暖白区块底 */
  --c-paper-deep: #F1EFE9;   /* 浅灰区块底 */
  --c-line:       #E4E1DA;   /* 分隔线 */
  --c-line-dark:  rgba(255, 255, 255, .18);
  --c-accent:     #B08D57;   /* 品牌点缀（黄铜） */
  --c-accent-dk:  #8C6E40;
  --c-overlay:    rgba(20, 23, 26, .55);

  /* 字体 */
  --ff-sans: "Inter", "Helvetica Neue", -apple-system, BlinkMacSystemFont,
             "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  --ff-display: "Optima", "Palatino Linotype", Georgia, "Songti SC", serif;

  /* 流体字号（移动端 → 桌面端自动缩放，无需断点） */
  --fs-eyebrow: clamp(.6875rem, .64rem + .18vw, .8125rem);
  --fs-body:    clamp(.9375rem, .9rem + .2vw, 1.0625rem);
  --fs-lead:    clamp(1.0625rem, 1rem + .5vw, 1.375rem);
  --fs-h4:      clamp(1.125rem, 1.05rem + .4vw, 1.375rem);
  --fs-h3:      clamp(1.375rem, 1.2rem + .9vw, 2rem);
  --fs-h2:      clamp(1.875rem, 1.4rem + 2.2vw, 3.5rem);
  --fs-h1:      clamp(2.5rem, 1.6rem + 4.4vw, 6rem);

  /* 间距节奏 */
  --sp-1: .5rem;  --sp-2: 1rem;   --sp-3: 1.5rem;  --sp-4: 2rem;
  --sp-5: 3rem;   --sp-6: 4rem;   --sp-7: 6rem;    --sp-8: 8rem;
  --sec-y: clamp(4rem, 3rem + 5vw, 8.5rem);        /* 区块上下留白 */
  --gutter: clamp(1.25rem, 1rem + 2vw, 3.5rem);    /* 左右安全边距 */
  --maxw: 1440px;                                   /* 内容最大宽度 */
  --maxw-text: 68ch;

  /* 其它 */
  --radius: 2px;             /* 品牌偏硬朗，圆角极小 */
  --radius-lg: 4px;
  --dur: .55s;
  --ease: cubic-bezier(.22, .61, .36, 1);
  --header-h: 72px;
}

/* ---------- 2. 基础重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-h);
}

body {
  font-family: var(--ff-sans);
  font-size: var(--fs-body);
  line-height: 1.7;
  color: var(--c-body);
  background: var(--c-paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

img, svg, video { display: block; max-width: 100%; height: auto; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
ul, ol { list-style: none; }
table { border-collapse: collapse; width: 100%; }
input, textarea, select { font: inherit; color: inherit; }

:focus-visible {
  outline: 2px solid var(--c-accent);
  outline-offset: 3px;
}

/* ---------- 3. 排版 ---------- */
h1, h2, h3, h4 {
  color: var(--c-ink);
  font-weight: 500;
  line-height: 1.12;
  letter-spacing: -.015em;
  text-wrap: balance;
}
h1 { font-size: var(--fs-h1); }
h2 { font-size: var(--fs-h2); }
h3 { font-size: var(--fs-h3); }
h4 { font-size: var(--fs-h4); line-height: 1.35; }

/* 小标签：全大写 + 宽字距（参考站的标志手法） */
.eyebrow {
  display: inline-block;
  font-size: var(--fs-eyebrow);
  font-weight: 600;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--c-accent);
}
.eyebrow--muted { color: var(--c-muted); }
.eyebrow--light { color: rgba(255, 255, 255, .75); }

.lead {
  font-size: var(--fs-lead);
  line-height: 1.6;
  color: var(--c-body);
  max-width: var(--maxw-text);
}

/* ---------- 4. 布局容器与栅格 ---------- */
.container {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.container--narrow { max-width: 980px; }

.section { padding-block: var(--sec-y); }
.section--warm  { background: var(--c-paper-warm); }
.section--deep  { background: var(--c-paper-deep); }
.section--dark  { background: var(--c-ink); color: rgba(255, 255, 255, .72); }
.section--dark h2,
.section--dark h3,
.section--dark h4 { color: #fff; }

/* 12 栅格 */
.grid {
  display: grid;
  gap: clamp(1.5rem, 1rem + 2vw, 3rem);
  grid-template-columns: repeat(12, minmax(0, 1fr));
}
.col-3  { grid-column: span 12; }
.col-4  { grid-column: span 12; }
.col-6  { grid-column: span 12; }
.col-8  { grid-column: span 12; }
.col-12 { grid-column: span 12; }

/* 区块标题组 */
.sec-head {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: clamp(2rem, 1.5rem + 2vw, 4rem);
}
.sec-head--center { align-items: center; text-align: center; }
.sec-head--split {
  flex-direction: row;
  align-items: flex-end;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}

/* ---------- 5. 通用组件 ---------- */
.btn {
  --btn-bg: var(--c-ink);
  --btn-fg: #fff;
  --btn-bd: var(--c-ink);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .6rem;
  padding: .95rem 1.9rem;
  background: var(--btn-bg);
  color: var(--btn-fg);
  border: 1px solid var(--btn-bd);
  border-radius: var(--radius);
  font-size: .8125rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background .3s var(--ease), color .3s var(--ease),
              border-color .3s var(--ease), transform .3s var(--ease);
}
.btn:hover { transform: translateY(-2px); }
.btn:active { transform: translateY(0); }
.btn__arrow { transition: transform .3s var(--ease); }
.btn:hover .btn__arrow { transform: translateX(4px); }

.btn--outline { --btn-bg: transparent; --btn-fg: var(--c-ink); --btn-bd: var(--c-ink); }
.btn--outline:hover { --btn-bg: var(--c-ink); --btn-fg: #fff; }

.btn--light { --btn-bg: #fff; --btn-fg: var(--c-ink); --btn-bd: #fff; }
.btn--light:hover { --btn-bg: var(--c-accent); --btn-fg: #fff; --btn-bd: var(--c-accent); }

.btn--ghost-light { --btn-bg: transparent; --btn-fg: #fff; --btn-bd: var(--c-line-dark); }
.btn--ghost-light:hover { --btn-bg: #fff; --btn-fg: var(--c-ink); --btn-bd: #fff; }

.btn--sm { padding: .7rem 1.35rem; font-size: .75rem; }

/* 文本链接（带下划线动画） */
.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  font-size: .8125rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--c-ink);
  padding-bottom: .25rem;
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 100% 1px;
  background-repeat: no-repeat;
  background-position: 0 100%;
  transition: background-size .4s var(--ease), color .3s var(--ease);
}
.link-arrow:hover { background-size: 0% 1px; color: var(--c-accent); }

/* 分隔线 */
.divider { height: 1px; background: var(--c-line); border: 0; }
.section--dark .divider { background: var(--c-line-dark); }

/* 图片通用外框 */
.media { position: relative; overflow: hidden; background: var(--c-paper-deep); }
.media img { width: 100%; height: 100%; object-fit: cover; transition: transform .9s var(--ease); }
.media--zoom:hover img { transform: scale(1.045); }

/* 比例控制（避免 CLS） */
.ratio-16x9 { aspect-ratio: 16 / 9; }
.ratio-4x3  { aspect-ratio: 4 / 3; }
.ratio-3x4  { aspect-ratio: 3 / 4; }
.ratio-1x1  { aspect-ratio: 1 / 1; }

/* ---------- 6. 区块样式 ---------- */

/* 6.1 Hero */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: flex-end;
  padding-block: calc(var(--header-h) + 3rem) clamp(2.5rem, 2rem + 3vw, 5rem);
  color: #fff;
  isolation: isolate;
  overflow: hidden;
}
.hero__bg { position: absolute; inset: 0; z-index: -2; }
.hero__bg img { width: 100%; height: 100%; object-fit: cover; will-change: transform; }
.hero__scrim {
  position: absolute; inset: 0; z-index: -1;
  background: linear-gradient(180deg,
              rgba(20,23,26,.55) 0%, rgba(20,23,26,.25) 40%, rgba(20,23,26,.85) 100%);
}
.hero__inner { width: 100%; will-change: transform, opacity; }
.hero h1 { color: #fff; margin-block: 1rem 1.5rem; max-width: 16ch; }
.hero__sub { color: rgba(255,255,255,.85); max-width: 52ch; font-size: var(--fs-lead); }
.hero__cta { display: flex; flex-wrap: wrap; gap: 1rem; margin-top: 2.25rem; }

.hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.5rem 2rem;
  margin-top: clamp(2.5rem, 2rem + 3vw, 4.5rem);
  padding-top: 2rem;
  border-top: 1px solid var(--c-line-dark);
}
/* dt 在前（语义正确），用 column-reverse 让数字显示在标签上方 */
.hero__stats .stat { display: flex; flex-direction: column-reverse; }
.stat__num { display: block; font-size: clamp(1.75rem, 1.4rem + 1.4vw, 2.75rem); color: #fff; font-weight: 400; line-height: 1; }
.stat__num small { font-size: .45em; letter-spacing: .1em; margin-left: .15em; }
.stat__lbl { font-size: .75rem; letter-spacing: .16em; text-transform: uppercase; color: rgba(255,255,255,.6); margin-top: .5rem; display: block; }

/* 6.2 品牌宣言 */
.manifesto { display: grid; gap: clamp(2rem, 1.5rem + 3vw, 4rem); }
.manifesto__text p + p { margin-top: 1.25rem; }
.signature { margin-top: 2rem; font-family: var(--ff-display); font-size: 1.125rem; color: var(--c-ink); }

/* 6.3 系列卡片（4 列 → 2 列 → 1 列） */
.series-grid {
  display: grid;
  gap: clamp(1.25rem, 1rem + 1.5vw, 2.25rem);
  grid-template-columns: 1fr;
}
.series-card {
  position: relative;
  display: block;
  overflow: hidden;
  background: var(--c-ink);
  color: #fff;
  border-radius: var(--radius);
}
.series-card .media { aspect-ratio: 1 / 1; }
.series-card .media img { opacity: .82; }
.series-card__body {
  position: absolute; inset: auto 0 0 0;
  padding: clamp(1.25rem, 1rem + 1vw, 2rem);
  background: linear-gradient(0deg, rgba(20,23,26,.9) 0%, rgba(20,23,26,0) 100%);
  display: flex; flex-direction: column; gap: .4rem;
}
.series-card__idx {
  font-size: .6875rem; letter-spacing: .2em; color: var(--c-accent); font-weight: 600;
}
.series-card__title { color: #fff; font-size: var(--fs-h4); }
.series-card__desc { font-size: .875rem; color: rgba(255,255,255,.72); }
.series-card:hover .media img { transform: scale(1.05); }

/* 6.4 能力优势 */
.feature {
  position: relative;
  display: flex; flex-direction: column; gap: .85rem;
  padding-block: 1.5rem;
  border-top: 1px solid var(--c-line);
}
.feature::after,
.step::after {
  content: "";
  position: absolute;
  left: 0;
  top: -1px;
  width: 100%;
  height: 1px;
  background: var(--c-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform .9s var(--ease) .1s;
}
.feature.is-visible::after,
.step.is-visible::after { transform: scaleX(1); }
.feature__icon {
  width: 40px; height: 40px; display: grid; place-items: center;
  color: var(--c-accent);
}
.feature__icon svg { width: 100%; height: 100%; }
.feature p { font-size: .9375rem; }

/* 6.5 材料对比 */
.material-card {
  display: flex; flex-direction: column;
  background: var(--c-paper);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  overflow: hidden;
  height: 100%;
}
.material-card .media { aspect-ratio: 1 / 1; }
.material-card__body { padding: clamp(1.25rem, 1rem + 1vw, 1.75rem); display: flex; flex-direction: column; gap: .75rem; flex: 1; }
.material-card__tag {
  align-self: flex-start;
  font-size: .625rem; letter-spacing: .16em; text-transform: uppercase; font-weight: 700;
  padding: .3rem .6rem; background: var(--c-paper-deep); color: var(--c-ink-soft);
}
.spec-list { margin-top: auto; padding-top: 1rem; border-top: 1px solid var(--c-line); display: grid; gap: .5rem; }
.spec-list li { display: flex; justify-content: space-between; gap: 1rem; font-size: .8125rem; }
.spec-list dt, .spec-list span:first-child { color: var(--c-muted); }
.spec-list span:last-child { color: var(--c-ink); font-weight: 500; text-align: right; }

/* 6.5b 产品预留位（media--slot）：后期放产品图的占位卡，替换为 .media>img 即可 */
.media--slot {
  aspect-ratio: 1 / 1;
  display: flex; align-items: center; justify-content: center;
  background: var(--c-paper-deep);
  border: 1px dashed var(--c-line);
}
.media-slot__label {
  font-size: .75rem; letter-spacing: .14em; text-transform: uppercase;
  color: var(--c-muted); text-align: center; padding: 0 1rem;
}

/* 6.6 应用场景画廊 */
.gallery {
  display: grid;
  gap: clamp(.75rem, .5rem + 1vw, 1.5rem);
  grid-template-columns: repeat(2, minmax(0, 1fr));
}
.gallery__item { position: relative; overflow: hidden; border-radius: var(--radius); }
.gallery__item .media { aspect-ratio: 4 / 3; }
.gallery__cap {
  position: absolute; inset: auto 0 0 0;
  padding: 1.25rem;
  background: linear-gradient(0deg, rgba(20,23,26,.85), transparent);
  color: #fff;
  font-size: .8125rem; letter-spacing: .1em; text-transform: uppercase;
}

/* 6.7 流程步骤 */
.steps { display: grid; gap: 2rem; grid-template-columns: 1fr; counter-reset: step; }
.step { position: relative; padding-top: 1.5rem; border-top: 1px solid var(--c-line); }
.section--dark .step { border-top-color: var(--c-line-dark); }
.step::before {
  counter-increment: step; content: "0" counter(step);
  display: block; font-size: .75rem; letter-spacing: .2em; color: var(--c-accent); margin-bottom: .85rem;
}
.step h4 { margin-bottom: .5rem; }
.step p { font-size: .9375rem; }

/* 6.8 证言轮播 */
.testimonials { position: relative; }
.tst-viewport { overflow: hidden; }
.tst-track { display: flex; transition: transform .6s var(--ease); }
.tst-slide { min-width: 100%; padding-right: 1rem; }
.tst-quote {
  font-family: var(--ff-display);
  font-size: clamp(1.25rem, 1.05rem + 1vw, 2rem);
  line-height: 1.45; color: var(--c-ink);
  max-width: 40ch;
}
.tst-meta { margin-top: 1.75rem; font-size: .8125rem; letter-spacing: .1em; text-transform: uppercase; color: var(--c-muted); }
.tst-nav { display: flex; gap: .75rem; margin-top: 2.5rem; }
.tst-dot {
  width: 36px; height: 2px; background: var(--c-line); border: 0; transition: background .3s var(--ease);
}
.tst-dot[aria-current="true"] { background: var(--c-accent); }

/* 6.9 FAQ 手风琴 */
.faq { border-top: 1px solid var(--c-line); }
.faq__item { border-bottom: 1px solid var(--c-line); }
.faq__q {
  width: 100%; display: flex; align-items: center; justify-content: space-between; gap: 1.5rem;
  padding: 1.5rem 0; text-align: left;
  font-size: var(--fs-h4); font-weight: 500; color: var(--c-ink);
  transition: color .3s var(--ease);
}
.faq__q:hover { color: var(--c-accent); }
.faq__icon { flex: none; width: 18px; height: 18px; position: relative; }
.faq__icon::before, .faq__icon::after {
  content: ""; position: absolute; inset: 50% 0 auto 0; height: 1px; background: currentColor;
  transition: transform .3s var(--ease);
}
.faq__icon::after { transform: rotate(90deg); }
.faq__item[data-open="true"] .faq__icon::after { transform: rotate(0deg); }
.faq__a { overflow: hidden; height: 0; transition: height .4s var(--ease); }
.faq__a > div { padding-bottom: 1.75rem; max-width: 70ch; }

/* 6.10 CTA 横幅 */
.cta-band { position: relative; isolation: isolate; padding-block: clamp(4rem, 3rem + 5vw, 8rem); color: #fff; text-align: center; }
.cta-band__bg { position: absolute; inset: 0; z-index: -2; }
.cta-band__bg img { width: 100%; height: 100%; object-fit: cover; }
.cta-band::after { content: ""; position: absolute; inset: 0; z-index: -1; background: rgba(20,23,26,.72); }
.cta-band h2 { color: #fff; margin-block: 1rem 1.25rem; }
.cta-band p { color: rgba(255,255,255,.8); max-width: 56ch; margin-inline: auto; }
.cta-band .hero__cta { justify-content: center; }
.cta-band__note {
  margin-top: 1.5rem;
  font-size: .8125rem;
  letter-spacing: .02em;
  color: rgba(255, 255, 255, .66);
}

/* ---------- 7. 页头 / 导航 ---------- */
.header {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  height: var(--header-h);
  display: flex; align-items: center;
  background: transparent;
  transition: background .4s var(--ease), box-shadow .4s var(--ease), color .4s var(--ease);
  color: #fff;
}
.header.is-stuck {
  background: rgba(255,255,255,.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--c-line);
  color: var(--c-ink);
}
.header__inner {
  width: 100%; max-width: var(--maxw); margin-inline: auto; padding-inline: var(--gutter);
  display: flex; align-items: center; justify-content: space-between; gap: 2rem;
}
.logo { display: inline-flex; align-items: center; gap: .55rem; font-size: 1.125rem; font-weight: 600; letter-spacing: .04em; white-space: nowrap; }
.logo__mark { width: 34px; height: 34px; object-fit: contain; flex: none; }
.logo sup { font-size: .5em; letter-spacing: 0; }
.logo span { font-weight: 300; opacity: .75; }

.nav { display: none; }
.nav__list { display: flex; align-items: center; gap: clamp(1.25rem, 1rem + 1vw, 2.25rem); }
.nav__link {
  position: relative;
  font-size: .8125rem; font-weight: 500; letter-spacing: .1em; text-transform: uppercase;
  padding-block: .35rem;
  transition: color .3s var(--ease);
}
.nav__link::after {
  content: ""; position: absolute; left: 0; bottom: 0; width: 0; height: 1px;
  background: currentColor; transition: width .35s var(--ease);
}
.nav__link:hover::after, .nav__link[aria-current="page"]::after { width: 100%; }
.nav__link:hover { color: var(--c-accent); }

.header__actions { display: none; align-items: center; gap: 1rem; }

.language-switch {
  border: 1px solid currentColor;
  border-radius: 999px;
  background: transparent;
  color: inherit;
  cursor: pointer;
  font: inherit;
  font-size: .72rem;
  letter-spacing: .08em;
  padding: .58rem .85rem;
  transition: background-color .2s ease, color .2s ease, border-color .2s ease;
}

.language-switch:hover,
.language-switch:focus-visible {
  background: var(--c-accent);
  border-color: var(--c-accent);
  color: #fff;
  outline: none;
}

.language-switch--drawer { align-self: flex-start; color: #fff; }

/* 汉堡按钮 */
.burger {
  display: inline-flex; flex-direction: column; justify-content: center; gap: 5px;
  width: 44px; height: 44px; padding: 10px; margin-right: -10px;
}
.burger span { display: block; height: 1.5px; width: 100%; background: currentColor; transition: transform .35s var(--ease), opacity .25s var(--ease); }
.burger[aria-expanded="true"] span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.burger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.burger[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* 移动端抽屉 */
.drawer {
  position: fixed; inset: 0; z-index: 99;
  background: var(--c-ink); color: #fff;
  padding: calc(var(--header-h) + 2rem) var(--gutter) 2rem;
  display: flex; flex-direction: column;
  transform: translateX(100%);
  transition: transform .45s var(--ease);
  overflow-y: auto;
}
.drawer.is-open { transform: translateX(0); }
.drawer__list { display: flex; flex-direction: column; gap: .25rem; }
.drawer__link {
  display: block; padding: 1rem 0;
  font-size: 1.5rem; font-weight: 400; color: #fff;
  border-bottom: 1px solid var(--c-line-dark);
  transition: color .3s var(--ease), padding-left .3s var(--ease);
}
.drawer__link:hover, .drawer__link:focus-visible { color: var(--c-accent); padding-left: .5rem; }
.drawer__foot { margin-top: auto; padding-top: 2.5rem; display: flex; flex-direction: column; gap: 1rem; }
.drawer__meta { font-size: .875rem; color: rgba(255,255,255,.6); }

body.is-locked { overflow: hidden; }

/* ---------- 8. 页脚 ---------- */
.footer { background: var(--c-ink); color: rgba(255,255,255,.65); padding-top: clamp(3rem, 2.5rem + 3vw, 5.5rem); }
.footer__grid { display: grid; gap: 2.5rem; grid-template-columns: 1fr; }
.footer__brand { display: flex; flex-direction: column; gap: 1.25rem; }
.footer .logo { font-size: 1.25rem; }
.footer .logo__mark { width: 38px; height: 38px; }
.footer__brand p { font-size: .9375rem; max-width: 34ch; }
.footer h5 {
  color: #fff; font-size: .75rem; font-weight: 600; letter-spacing: .18em; text-transform: uppercase;
  margin-bottom: 1.25rem;
}
.footer__list { display: flex; flex-direction: column; gap: .7rem; }
.footer__list a { font-size: .9375rem; transition: color .3s var(--ease); }
.footer__list a:hover { color: var(--c-accent); }
.footer__bottom {
  margin-top: clamp(2.5rem, 2rem + 2vw, 4rem);
  padding-block: 1.75rem;
  border-top: 1px solid var(--c-line-dark);
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 1rem;
  font-size: .8125rem;
}
.footer__legal { display: flex; flex-wrap: wrap; gap: 1.5rem; }
.footer__legal a:hover { color: var(--c-accent); }

/* ---------- 9. 动效 ---------- */
html.js .reveal { opacity: 0; transform: translateY(28px); transition: opacity .6s var(--ease), transform .6s var(--ease); }
html.js .reveal.is-visible { opacity: 1; transform: none; transition-duration: .8s; }

/* 滚动进度条 */
.progress {
  position: fixed; top: 0; left: 0; z-index: 101;
  height: 2px; width: 0%; background: var(--c-accent);
  transition: width .1s linear;
}

/* 返回顶部 */
.to-top {
  position: fixed; right: clamp(1rem, .5rem + 1.5vw, 2rem); bottom: clamp(1rem, .5rem + 1.5vw, 2rem);
  z-index: 90; width: 46px; height: 46px; display: grid; place-items: center;
  background: var(--c-ink); color: #fff; border-radius: 50%;
  opacity: 0; visibility: hidden; transform: translateY(12px);
  transition: opacity .35s var(--ease), transform .35s var(--ease), visibility .35s;
}
.to-top.is-visible { opacity: 1; visibility: visible; transform: none; }
.to-top:hover { background: var(--c-accent); }

/* ---------- 10. 响应式断点 ---------- */

/* —— 平板 ≥ 640px —— */
@media (min-width: 640px) {
  .hero__stats { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .series-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer__grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  /* 平板：优势 2 列；材料卡 2 列（4 列栅格下占半宽） */
  .col-3 { grid-column: span 6; }
  .col-4 { grid-column: span 6; }
}

/* —— 小桌面 ≥ 900px —— */
@media (min-width: 900px) {
  :root { --header-h: 84px; }
  .nav { display: block; }
  .header__actions { display: flex; }
  .burger { display: none; }
  .drawer { display: none; }

  .col-3  { grid-column: span 3; }
  .col-4  { grid-column: span 4; }
  .col-6  { grid-column: span 6; }
  .col-8  { grid-column: span 8; }

  .manifesto { grid-template-columns: 5fr 7fr; align-items: start; }
  .series-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .gallery { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .steps { grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 1.5rem; }
  .footer__grid { grid-template-columns: 2fr 1fr 1fr 1fr; }
  .split-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(2rem, 1.5rem + 3vw, 5rem); align-items: center; }
  .faq-layout { display: grid; grid-template-columns: 4fr 8fr; gap: clamp(2rem, 1.5rem + 3vw, 5rem); }
}

/* —— 大桌面 ≥ 1280px —— */
@media (min-width: 1280px) {
  .gallery { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

/* ---------- 11. 可访问性 / 偏好 ---------- */
.skip-link {
  position: absolute; left: -9999px; top: 0; z-index: 200;
  background: var(--c-ink); color: #fff; padding: .85rem 1.5rem;
}
.skip-link:focus { left: 1rem; top: 1rem; }

.visually-hidden {
  position: absolute !important; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
    scroll-behavior: auto !important;
  }
  html.js .reveal { opacity: 1; transform: none; }
}

/* 打印 */
@media print {
  .header, .drawer, .to-top, .progress, .cta-band { display: none !important; }
  body { color: #000; background: #fff; }
}