/* ==========================================================================
   桑皮纸展示站 - 全局样式
   PC / H5 同一套代码，断点：1024 / 768 / 520
   ========================================================================== */

:root {
  --paper: #f7f2e8;
  --paper-2: #efe6d6;
  --paper-3: #e5d9c5;
  --ink: #241f1a;
  --ink-2: #5a5045;
  --ink-3: #8b8073;
  --accent: #9c6b32;
  --accent-2: #7a4e22;
  --line: rgba(36, 31, 26, 0.12);
  --shadow: 0 10px 30px rgba(36, 31, 26, 0.08);
  --radius: 6px;
  --maxw: 1200px;
  --nav-h: 68px;
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", STSong,
    "SimSun", "Microsoft YaHei", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.75;
  font-size: 16px;
  overflow-x: hidden;
}
img,
svg {
  max-width: 100%;
  display: block;
}
a {
  color: inherit;
  text-decoration: none;
}
h1,
h2,
h3,
h4 {
  font-family: var(--font-serif);
  font-weight: 700;
  line-height: 1.35;
  margin: 0 0 0.6em;
  letter-spacing: 0.02em;
}
p {
  margin: 0 0 1em;
}
ul {
  margin: 0 0 1em;
  padding-left: 1.2em;
}
::selection {
  background: var(--accent);
  color: #fff;
}

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}
.section {
  padding: clamp(56px, 8vw, 104px) 0;
}
.section--tint {
  background: var(--paper-2);
}
.section--light {
  background: #fbf8f2;
}

/* ---------- 通用文字组件 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 13px;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 14px;
}
.eyebrow::before {
  content: "";
  width: 28px;
  height: 1px;
  background: var(--accent);
}
.section-title {
  font-size: clamp(26px, 3.4vw, 40px);
}
.section-desc {
  max-width: 62ch;
  color: var(--ink-2);
  font-size: clamp(15px, 1.2vw, 17px);
}
.center {
  text-align: center;
}
.center .section-desc {
  margin-left: auto;
  margin-right: auto;
}
.divider {
  width: 56px;
  height: 2px;
  background: var(--accent);
  margin: 18px 0 26px;
}
.center .divider {
  margin-left: auto;
  margin-right: auto;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 30px;
  border-radius: 999px;
  font-size: 15px;
  letter-spacing: 0.08em;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.25s ease;
  font-family: inherit;
}
.btn--primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 8px 20px rgba(156, 107, 50, 0.28);
}
.btn--primary:hover {
  background: var(--accent-2);
  transform: translateY(-2px);
}
.btn--ghost {
  border-color: var(--ink);
  color: var(--ink);
}
.btn--ghost:hover {
  background: var(--ink);
  color: var(--paper);
  transform: translateY(-2px);
}
.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 30px;
}

/* ==========================================================================
   顶部导航
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 242, 232, 0.92);
  backdrop-filter: saturate(160%) blur(8px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}
.brand-mark {
  width: 38px;
  height: 38px;
  border-radius: 4px;
  background: linear-gradient(140deg, var(--accent), var(--accent-2));
  color: #fff;
  display: grid;
  place-items: center;
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 700;
}
.brand-text {
  line-height: 1.2;
}
.brand-text b {
  font-family: var(--font-serif);
  font-size: 19px;
  letter-spacing: 0.16em;
  display: block;
}
.brand-text span {
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--ink-3);
  text-transform: uppercase;
}

.nav {
  display: flex;
  align-items: center;
  gap: clamp(14px, 2vw, 34px);
}
.nav a {
  position: relative;
  font-size: 15px;
  letter-spacing: 0.06em;
  padding: 6px 0;
  color: var(--ink-2);
  transition: color 0.2s;
  white-space: nowrap;
}
.nav a:hover {
  color: var(--accent);
}
.nav a.is-active {
  color: var(--accent-2);
  font-weight: 600;
}
.nav a.is-active::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -2px;
  height: 2px;
  background: var(--accent);
}
.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  border: 1px solid var(--line);
  background: transparent;
  border-radius: 4px;
  cursor: pointer;
  padding: 0;
}
.nav-toggle span {
  display: block;
  width: 20px;
  height: 1.5px;
  background: var(--ink);
  margin: 4px auto;
  transition: 0.25s;
}
.nav-toggle.is-open span:nth-child(1) {
  transform: translateY(5.5px) rotate(45deg);
}
.nav-toggle.is-open span:nth-child(2) {
  opacity: 0;
}
.nav-toggle.is-open span:nth-child(3) {
  transform: translateY(-5.5px) rotate(-45deg);
}

/* ==========================================================================
   首页 Hero
   ========================================================================== */
.hero {
  position: relative;
  padding: clamp(72px, 11vw, 132px) 0 clamp(60px, 8vw, 96px);
  background: linear-gradient(180deg, var(--paper-3), var(--paper) 70%);
  overflow: hidden;
}
.hero::before,
.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}
/* 纸张纤维纹理 */
.hero::before {
  background-image: repeating-linear-gradient(
      92deg,
      rgba(36, 31, 26, 0.035) 0 1px,
      transparent 1px 7px
    ),
    repeating-linear-gradient(
      3deg,
      rgba(156, 107, 50, 0.045) 0 1px,
      transparent 1px 11px
    );
}
.hero::after {
  background: radial-gradient(
    60% 60% at 82% 18%,
    rgba(156, 107, 50, 0.16),
    transparent 70%
  );
}
.hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: clamp(30px, 5vw, 68px);
  align-items: center;
}
.hero h1 {
  font-size: clamp(34px, 5.6vw, 62px);
  margin-bottom: 0.4em;
}
.hero h1 em {
  font-style: normal;
  color: var(--accent);
  position: relative;
}
.hero-sub {
  font-size: clamp(15px, 1.4vw, 18px);
  color: var(--ink-2);
  max-width: 46ch;
}
.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 26px;
  list-style: none;
  padding: 0;
}
.hero-tags li {
  font-size: 13px;
  letter-spacing: 0.1em;
  padding: 6px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.5);
}
.hero-visual {
  position: relative;
  aspect-ratio: 4 / 5;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.hero-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
/* 正文配图：沿用占位块的圆角与比例 */
.img-cover {
  width: 100%;
  object-fit: cover;
  border-radius: var(--radius);
  display: block;
}
.hero-badge {
  position: absolute;
  left: 18px;
  bottom: 18px;
  right: 18px;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 12px;
  padding: 16px 18px;
  background: rgba(36, 31, 26, 0.72);
  color: #fff;
  border-radius: 4px;
  backdrop-filter: blur(4px);
}
.hero-badge b {
  font-family: var(--font-serif);
  font-size: 17px;
  display: block;
}
.hero-badge span {
  font-size: 12px;
  opacity: 0.75;
  letter-spacing: 0.1em;
}

/* ==========================================================================
   通用网格 / 卡片
   ========================================================================== */
.grid {
  display: grid;
  gap: clamp(20px, 2.4vw, 30px);
}
.grid--2 {
  grid-template-columns: repeat(2, 1fr);
}
.grid--3 {
  grid-template-columns: repeat(3, 1fr);
}
.grid--4 {
  grid-template-columns: repeat(4, 1fr);
}

.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: clamp(22px, 2.4vw, 32px);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
}
.card h3 {
  font-size: 20px;
  margin-bottom: 0.5em;
}
.card p {
  color: var(--ink-2);
  font-size: 15px;
  margin-bottom: 0;
}
.card-num {
  font-family: var(--font-serif);
  font-size: 34px;
  color: var(--paper-3);
  line-height: 1;
  margin-bottom: 12px;
}

/* 图片占位块（替换为真实图片即可） */
.ph {
  position: relative;
  width: 100%;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--paper-3);
  background-image: repeating-linear-gradient(
      92deg,
      rgba(36, 31, 26, 0.04) 0 1px,
      transparent 1px 8px
    ),
    repeating-linear-gradient(
      2deg,
      rgba(156, 107, 50, 0.06) 0 1px,
      transparent 1px 13px
    ),
    linear-gradient(150deg, #e8dbc4, #d8c7a8 55%, #cbb693);
  display: grid;
  place-items: center;
}
.ph > span {
  font-size: 13px;
  letter-spacing: 0.18em;
  color: rgba(36, 31, 26, 0.5);
  background: rgba(255, 255, 255, 0.55);
  padding: 6px 14px;
  border-radius: 999px;
}
.ph--1x1 {
  aspect-ratio: 1 / 1;
}
.ph--4x3 {
  aspect-ratio: 4 / 3;
}
.ph--3x4 {
  aspect-ratio: 3 / 4;
}
.ph--16x9 {
  aspect-ratio: 16 / 9;
}

/* ---------- 数据条 ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: 30px 0;
}
.stat b {
  font-family: var(--font-serif);
  font-size: clamp(28px, 3.6vw, 44px);
  color: var(--accent-2);
  display: block;
  line-height: 1.1;
}
.stat span {
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
}

/* ---------- 双栏图文 ---------- */
.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(28px, 5vw, 64px);
  align-items: center;
}
.split--reverse .split-text {
  order: 2;
}

/* ---------- 工艺流程时间轴 ---------- */
.steps {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}
.steps::before {
  content: "";
  position: absolute;
  left: 23px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: var(--line);
}
.step {
  position: relative;
  padding-left: 66px;
  padding-bottom: 34px;
}
.step:last-child {
  padding-bottom: 0;
}
.step i {
  position: absolute;
  left: 0;
  top: 0;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: var(--paper);
  border: 1px solid var(--accent);
  color: var(--accent-2);
  display: grid;
  place-items: center;
  font-style: normal;
  font-family: var(--font-serif);
  font-weight: 700;
}
.step h3 {
  font-size: 19px;
  margin-bottom: 0.35em;
}
.step p {
  color: var(--ink-2);
  font-size: 15px;
  margin-bottom: 0;
}

/* ---------- 产品 ---------- */
.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-bottom: 34px;
}
.filter-btn {
  border: 1px solid var(--line);
  background: transparent;
  padding: 8px 20px;
  border-radius: 999px;
  font-size: 14px;
  cursor: pointer;
  font-family: inherit;
  color: var(--ink-2);
  transition: 0.2s;
}
.filter-btn.is-active,
.filter-btn:hover {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}
.product {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.product .ph,
.product .img-cover {
  border-radius: 0;
}
.product-body {
  padding: 20px 22px 24px;
}
.product-body h3 {
  font-size: 18px;
  margin-bottom: 0.3em;
}
.product-meta {
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0.1em;
  margin-bottom: 10px;
}
.product-body p {
  font-size: 14px;
  color: var(--ink-2);
  margin-bottom: 0;
}

/* ---------- 时间线（历史） ---------- */
.timeline {
  display: grid;
  gap: 2px;
}
.tl-item {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 24px;
  padding: 22px 0;
  border-top: 1px solid var(--line);
}
.tl-item:last-child {
  border-bottom: 1px solid var(--line);
}
.tl-year {
  font-family: var(--font-serif);
  font-size: 22px;
  color: var(--accent-2);
}
.tl-item p {
  margin: 0;
  color: var(--ink-2);
  font-size: 15px;
}
.tl-item h3 {
  font-size: 17px;
  margin-bottom: 0.3em;
}

/* ---------- 联系 / 表单 ---------- */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(28px, 5vw, 60px);
  align-items: start;
}
.info-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.info-list li {
  display: flex;
  gap: 14px;
  padding: 16px 0;
  border-bottom: 1px dashed var(--line);
  font-size: 15px;
}
.info-list b {
  min-width: 74px;
  color: var(--ink-3);
  font-weight: 400;
  letter-spacing: 0.1em;
}
.field {
  margin-bottom: 16px;
}
.field label {
  display: block;
  font-size: 13px;
  letter-spacing: 0.12em;
  color: var(--ink-3);
  margin-bottom: 7px;
}
.field input,
.field textarea,
.field select {
  width: 100%;
  font: inherit;
  font-size: 15px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: #fff;
  color: var(--ink);
}
.field input:focus,
.field textarea:focus,
.field select:focus {
  outline: none;
  border-color: var(--accent);
}
.field textarea {
  resize: vertical;
  min-height: 110px;
}
.form-note {
  font-size: 13px;
  color: var(--ink-3);
}

/* ---------- CTA ---------- */
.cta {
  background: linear-gradient(120deg, var(--ink) 0%, #3a3129 100%);
  color: var(--paper);
  text-align: center;
  padding: clamp(56px, 8vw, 96px) 0;
}
.cta h2 {
  font-size: clamp(24px, 3.2vw, 36px);
}
.cta p {
  color: rgba(247, 242, 232, 0.7);
  max-width: 52ch;
  margin: 0 auto 8px;
}
.cta .btn--primary {
  background: var(--accent);
}

/* ==========================================================================
   底部
   ========================================================================== */
.site-footer {
  background: #1e1a16;
  color: rgba(247, 242, 232, 0.72);
  padding: clamp(46px, 6vw, 72px) 0 26px;
  font-size: 14px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 34px;
}
.site-footer h4 {
  color: var(--paper);
  font-size: 16px;
  letter-spacing: 0.14em;
  margin-bottom: 18px;
}
.site-footer ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.site-footer li {
  margin-bottom: 10px;
}
.site-footer a:hover {
  color: var(--accent);
}
.footer-bottom {
  margin-top: 40px;
  padding-top: 20px;
  border-top: 1px solid rgba(247, 242, 232, 0.14);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: space-between;
  font-size: 13px;
  color: rgba(247, 242, 232, 0.5);
}

/* ---------- 返回顶部 ---------- */
.to-top {
  position: fixed;
  right: 22px;
  bottom: 22px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 1px solid var(--line);
  background: rgba(247, 242, 232, 0.92);
  color: var(--ink);
  cursor: pointer;
  display: grid;
  place-items: center;
  opacity: 0;
  visibility: hidden;
  transition: 0.25s;
  z-index: 90;
  backdrop-filter: blur(6px);
  font-size: 18px;
}
.to-top.is-show {
  opacity: 1;
  visibility: visible;
}

/* ---------- 滚动入场动画 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(22px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.reveal.is-in {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  html {
    scroll-behavior: auto;
  }
}

/* ==========================================================================
   响应式：平板
   ========================================================================== */
@media (max-width: 1024px) {
  .grid--4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .grid--3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 36px;
  }
  .hero-visual {
    aspect-ratio: 16 / 10;
    order: -1;
  }
}

/* ==========================================================================
   响应式：手机
   ========================================================================== */
@media (max-width: 768px) {
  body {
    font-size: 15px;
  }
  :root {
    --nav-h: 60px;
  }
  .container {
    padding: 0 18px;
  }
  .nav-toggle {
    display: block;
  }
  .nav {
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--paper);
    border-bottom: 1px solid var(--line);
    box-shadow: var(--shadow);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.32s ease;
  }
  .nav.is-open {
    max-height: 340px;
  }
  .nav a {
    padding: 15px 18px;
    border-top: 1px solid var(--line);
    font-size: 16px;
    white-space: normal;
  }
  .nav a.is-active::after {
    display: none;
  }
  .nav a.is-active {
    background: var(--paper-2);
  }
  .grid--2,
  .grid--3,
  .grid--4,
  .split,
  .contact-grid {
    grid-template-columns: 1fr;
  }
  .split--reverse .split-text {
    order: 0;
  }
  .stats {
    grid-template-columns: repeat(2, 1fr);
    gap: 26px 16px;
  }
  .tl-item {
    grid-template-columns: 1fr;
    gap: 6px;
  }
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 26px;
  }
  .hero-tags li {
    font-size: 12px;
  }
  .hero-badge {
    position: static;
    background: var(--ink);
    border-radius: 0 0 var(--radius) var(--radius);
  }
  .btn {
    flex: 1 1 auto;
  }
  .to-top {
    right: 14px;
    bottom: 14px;
  }
}

@media (max-width: 520px) {
  .hero h1 {
    font-size: 30px;
  }
  .stats {
    grid-template-columns: repeat(2, 1fr);
  }
  .step {
    padding-left: 58px;
  }
  .step i {
    width: 40px;
    height: 40px;
  }
  .steps::before {
    left: 20px;
  }
  .brand-text span {
    display: none;
  }
}