/* ==========================================================
   童行研学 — 站点样式
   设计原则：高级而克制。大量留白、柔和自然色、细腻动效。
   断点：手机 < 640px ≤ 平板 < 1024px ≤ 桌面
   ========================================================== */

/* ---------- 设计变量 ---------- */
:root {
  /* 色板：森林绿 + 暖橙 + 米白 */
  --c-ink: #22302a;          /* 主文字（墨绿黑） */
  --c-ink-soft: #5b6b63;     /* 次级文字 */
  --c-primary: #2f6b4f;      /* 森林绿 */
  --c-primary-deep: #24523d;
  --c-accent: #f4a259;       /* 暖橙点缀 */
  --c-bg: #fffdf8;           /* 米白底 */
  --c-bg-alt: #f4f1e8;       /* 浅卡其分区底 */
  --c-line: #e5e0d3;

  --font-serif: "Noto Serif SC", "Songti SC", serif;
  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;

  --radius: 18px;
  --shadow-sm: 0 2px 10px rgba(34, 48, 42, .06);
  --shadow-md: 0 12px 32px rgba(34, 48, 42, .10);

  --ease-out: cubic-bezier(.22, .8, .35, 1);
  --container: 1160px;
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 400;
  color: var(--c-ink);
  background: var(--c-bg);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { font-family: var(--font-serif); line-height: 1.35; margin: 0; }
p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
figure { margin: 0; }
button { font-family: inherit; }

.container {
  width: min(var(--container), 100% - 48px);
  margin-inline: auto;
}

/* ---------- 滚动进入动画（配合 js 的 .in 类） ---------- */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .8s var(--ease-out), transform .8s var(--ease-out);
}
.reveal.in { opacity: 1; transform: none; }
/* 级联延迟：同组元素依次浮现 */
.reveal.d1 { transition-delay: .12s; }
.reveal.d2 { transition-delay: .24s; }
.reveal.d3 { transition-delay: .36s; }
.reveal.d4 { transition-delay: .48s; }

/* 用户偏好减少动效时，全部直接呈现 */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1 !important; transform: none !important; transition: none !important; }
  * { animation: none !important; }
}

/* ---------- 顶部导航 ---------- */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  padding: 18px 0;
  transition: padding .4s var(--ease-out), color .4s;
  color: #fff;
}
/* 头部背景放在伪元素上：
   若把 backdrop-filter 直接加在 header 上，会使内部
   position:fixed 的移动端抽屉菜单相对 header 定位而失效。 */
.site-header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: transparent;
  transition: background .4s var(--ease-out), box-shadow .4s var(--ease-out);
}
/* 滚动后变为浅色实底 */
.site-header.scrolled { padding: 10px 0; color: var(--c-ink); }
.site-header.scrolled::before {
  background: rgba(255, 253, 248, .92);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
}

.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; }

.brand { display: inline-flex; align-items: center; gap: 10px; }
.brand-mark { width: 34px; height: 34px; flex: 0 0 auto; }
.brand-name { font-family: var(--font-serif); font-size: 1.25rem; font-weight: 700; letter-spacing: .06em; white-space: nowrap; }

.site-nav { display: flex; align-items: center; gap: clamp(14px, 2.2vw, 28px); font-size: .95rem; }
.site-nav a { position: relative; padding: 4px 0; opacity: .9; transition: opacity .3s; white-space: nowrap; }
.site-nav a:hover { opacity: 1; }
/* 下划线滑入效果 */
.site-nav a:not(.nav-cta)::after {
  content: "";
  position: absolute;
  left: 0; bottom: -2px;
  width: 100%; height: 2px;
  background: currentColor;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform .35s var(--ease-out);
}
.site-nav a:not(.nav-cta):hover::after { transform: scaleX(1); transform-origin: left; }

.nav-cta {
  padding: 8px 20px !important;
  border-radius: 999px;
  background: var(--c-accent);
  color: #fff !important;
  font-weight: 500;
  transition: transform .3s var(--ease-out), box-shadow .3s var(--ease-out);
}
.nav-cta:hover { transform: translateY(-2px); box-shadow: 0 8px 18px rgba(244, 162, 89, .4); }

/* 汉堡按钮（默认隐藏，移动端显示） */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: 0;
  padding: 8px;
  cursor: pointer;
  color: inherit;
  /* 需高于打开的抽屉（z-index:99），否则被遮住无法关闭 */
  position: relative;
  z-index: 101;
}
/* 抽屉打开时按钮浮在深色背景上，固定为白色 */
.nav-toggle.open { color: #fff; }
.nav-toggle span {
  width: 24px; height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform .35s var(--ease-out), opacity .3s;
}
/* 展开态：三横变叉 */
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- Hero 首屏 ---------- */
.hero {
  position: relative;
  min-height: 100svh;
  display: grid;
  place-items: center;
  color: #fff;
  overflow: hidden;
  text-align: center;
}
.hero-bg, .hero-bg img {
  position: absolute; inset: 0;
  width: 100%; height: 100%;
  object-fit: cover;
}
/* 缓慢的 Ken Burns 呼吸感 */
.hero-bg img { animation: kenburns 26s var(--ease-out) both; }
@keyframes kenburns {
  from { transform: scale(1.08); }
  to   { transform: scale(1); }
}
/* 深色渐变罩，保证文字可读 */
.hero-veil {
  position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(20, 30, 25, .55) 0%, rgba(20, 30, 25, .25) 45%, rgba(20, 30, 25, .6) 100%);
}
.hero-content { position: relative; z-index: 1; padding: 120px 0 80px; }

.hero-kicker {
  display: inline-block;
  padding: 6px 18px;
  border: 1px solid rgba(255, 255, 255, .5);
  border-radius: 999px;
  font-size: .85rem;
  letter-spacing: .2em;
  margin-bottom: 28px;
}
.hero-title {
  font-size: clamp(2rem, 5.6vw, 3.6rem);
  font-weight: 700;
  letter-spacing: .04em;
}
.hero-title span { display: block; }
.hero-sub {
  margin-top: 22px;
  font-size: clamp(.95rem, 2vw, 1.1rem);
  font-weight: 300;
  opacity: .92;
  letter-spacing: .04em;
}
.hero-actions {
  margin-top: 40px;
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* 按钮体系 */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 32px;
  border-radius: 999px;
  font-size: .95rem;
  font-weight: 500;
  letter-spacing: .05em;
  transition: transform .3s var(--ease-out), box-shadow .3s var(--ease-out), background .3s;
}
.btn:hover { transform: translateY(-3px); }
.btn svg { width: 18px; height: 18px; }

.btn-primary { background: var(--c-accent); color: #fff; }
.btn-primary:hover { box-shadow: 0 12px 26px rgba(244, 162, 89, .45); }
.btn-ghost { border: 1.5px solid rgba(255, 255, 255, .75); color: #fff; }
.btn-ghost:hover { background: rgba(255, 255, 255, .12); }
.btn-light { background: #fff; color: var(--c-primary-deep); }
.btn-light:hover { box-shadow: 0 12px 26px rgba(0, 0, 0, .18); }
.btn-outline-light { border: 1.5px solid rgba(255, 255, 255, .8); color: #fff; }
.btn-outline-light:hover { background: rgba(255, 255, 255, .12); }

/* 向下滚动提示：轻微浮动 */
.scroll-hint {
  position: absolute;
  bottom: 30px; left: 50%;
  transform: translateX(-50%);
  width: 40px; height: 40px;
  display: grid; place-items: center;
  color: rgba(255, 255, 255, .85);
  animation: float 2.6s ease-in-out infinite;
}
.scroll-hint svg { width: 22px; height: 22px; }
@keyframes float {
  0%, 100% { transform: translate(-50%, 0); }
  50% { transform: translate(-50%, 8px); }
}

/* ---------- 数据一览 ---------- */
.stats { background: var(--c-primary-deep); color: #fff; padding: 64px 0; }
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  text-align: center;
}
.stat-num {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 4vw, 2.8rem);
  font-weight: 700;
  color: var(--c-accent);
}
.stat-num i { font-style: normal; font-size: .6em; margin-left: 2px; }
.stat-label { margin-top: 6px; font-size: .9rem; opacity: .82; letter-spacing: .08em; }

/* ---------- 通用分区 ---------- */
.section { padding: 110px 0; }
.section-head { max-width: 640px; margin: 0 auto 64px; text-align: center; }
.section-kicker {
  color: var(--c-accent);
  font-size: .85rem;
  font-weight: 500;
  letter-spacing: .3em;
  margin-bottom: 14px;
}
.section-title {
  font-size: clamp(1.6rem, 3.6vw, 2.3rem);
  font-weight: 700;
  letter-spacing: .04em;
}
.section-desc { margin-top: 18px; color: var(--c-ink-soft); font-size: .98rem; }

/* ---------- 研学课程卡片 ---------- */
.course-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}
.course-card {
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 40px 32px;
  transition: transform .45s var(--ease-out), box-shadow .45s var(--ease-out), border-color .45s;
}
.course-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-md);
  border-color: transparent;
}
.course-icon {
  width: 64px; height: 64px;
  border-radius: 18px;
  display: grid; place-items: center;
  background: rgba(47, 107, 79, .08);
  color: var(--c-primary);
  margin-bottom: 24px;
  transition: background .4s, color .4s, transform .45s var(--ease-out);
}
.course-card:hover .course-icon {
  background: var(--c-primary);
  color: #fff;
  transform: rotate(-6deg) scale(1.05);
}
.course-icon svg { width: 34px; height: 34px; }
.course-card h3 { font-size: 1.2rem; margin-bottom: 12px; }
.course-card p { color: var(--c-ink-soft); font-size: .93rem; }
.course-meta {
  margin-top: 18px !important;
  color: var(--c-accent) !important;
  font-weight: 500;
  font-size: .85rem !important;
  letter-spacing: .08em;
}

/* ---------- 图文交错分区 ---------- */
.split { background: var(--c-bg-alt); }
.split-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 72px;
  align-items: center;
}
.split-reverse .split-media { order: 2; }
.split-media {
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-md);
}
.split-media img {
  width: 100%;
  aspect-ratio: 4 / 3.4;
  object-fit: cover;
  transition: transform .8s var(--ease-out);
}
.split-media:hover img { transform: scale(1.04); }
.split-body .section-title { margin-top: 6px; }

.check-list { margin-top: 30px; display: grid; gap: 16px; }
.check-list li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  color: var(--c-ink-soft);
  font-size: .95rem;
}
.check-list svg {
  flex: 0 0 auto;
  width: 20px; height: 20px;
  margin-top: 4px;
  color: var(--c-primary);
}

/* ---------- 营地基地 ---------- */
.camp-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}
.camp-card {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  aspect-ratio: 3 / 3.8;
  box-shadow: var(--shadow-sm);
}
.camp-card img {
  width: 100%; height: 100%;
  object-fit: cover;
  transition: transform .8s var(--ease-out);
}
.camp-card:hover img { transform: scale(1.06); }
.camp-info {
  position: absolute;
  inset: auto 0 0 0;
  padding: 60px 26px 24px;
  color: #fff;
  background: linear-gradient(180deg, transparent, rgba(20, 30, 25, .8));
}
.camp-info h3 { font-size: 1.15rem; margin-bottom: 6px; }
.camp-info p { font-size: .85rem; opacity: .88; }

/* ---------- 安全保障 ---------- */
.safety { background: var(--c-bg); }
.safety-list { margin-top: 34px; display: grid; gap: 30px; }
.safety-item { display: flex; gap: 20px; align-items: flex-start; }
.safety-icon {
  flex: 0 0 auto;
  width: 56px; height: 56px;
  border-radius: 16px;
  display: grid; place-items: center;
  background: rgba(244, 162, 89, .12);
  color: var(--c-accent);
}
.safety-icon svg { width: 30px; height: 30px; }
.safety-item h3 { font-size: 1.08rem; margin-bottom: 6px; }
.safety-item p { color: var(--c-ink-soft); font-size: .92rem; }

/* ---------- 精彩瞬间画廊 ---------- */
.moments { background: var(--c-bg-alt); padding-bottom: 0; }
.gallery {
  margin-top: 8px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}
.gallery figure { overflow: hidden; }
.gallery img {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  filter: saturate(.92);
  transition: transform .8s var(--ease-out), filter .6s;
}
.gallery figure:hover img { transform: scale(1.07); filter: saturate(1.05); }

/* ---------- 家长评价（4 条引述，桌面端 2×2 平衡布局） ---------- */
.voice-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 28px;
}
.voice-card {
  margin: 0;
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 36px 30px;
  transition: transform .45s var(--ease-out), box-shadow .45s var(--ease-out);
}
.voice-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-md); }
.quote-mark { width: 30px; height: 30px; color: var(--c-accent); opacity: .8; margin-bottom: 18px; }
.voice-card p { color: var(--c-ink-soft); font-size: .95rem; }
.voice-card footer { margin-top: 22px; font-size: .85rem; color: var(--c-ink); font-weight: 500; }

/* ---------- 报名流程 ---------- */
.steps { background: var(--c-bg-alt); }
.step-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 28px;
  counter-reset: step;
}
.step {
  background: #fff;
  border-radius: var(--radius);
  padding: 36px 28px;
  border: 1px solid var(--c-line);
}
.step-num {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 700;
  color: var(--c-accent);
  display: block;
  margin-bottom: 14px;
}
.step h3 { font-size: 1.1rem; margin-bottom: 8px; }
.step p { color: var(--c-ink-soft); font-size: .9rem; }

/* ---------- 底部 CTA ---------- */
.cta-band {
  background:
    linear-gradient(120deg, rgba(36, 82, 61, .94), rgba(47, 107, 79, .88)),
    url("https://images.unsplash.com/photo-1476234251651-f353703a034d?q=80&w=1800&auto=format&fit=crop") center/cover;
  color: #fff;
  padding: 100px 0;
  text-align: center;
}
.cta-inner h2 { font-size: clamp(1.5rem, 3.4vw, 2.2rem); }
.cta-inner p { margin-top: 14px; opacity: .9; }
.cta-actions {
  margin-top: 36px;
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ---------- 页脚 ---------- */
.site-footer { background: #1c2722; color: rgba(255, 255, 255, .78); padding: 72px 0 0; }
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 40px;
  padding-bottom: 56px;
}
.footer-brand .brand { color: #fff; }
.footer-brand p { margin-top: 18px; font-size: .9rem; line-height: 2; }
.footer-col h4 { color: #fff; font-size: 1rem; margin-bottom: 18px; }
.footer-col a { display: block; font-size: .9rem; padding: 5px 0; opacity: .78; transition: opacity .3s, transform .3s var(--ease-out); }
.footer-col a:hover { opacity: 1; transform: translateX(4px); }
.footer-col p { font-size: .9rem; line-height: 2.1; }
.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, .12);
  padding: 22px 0;
  font-size: .8rem;
  opacity: .6;
  text-align: center;
}
.footer-bottom p {
  max-width: 100%;
  overflow-wrap: break-word;
  word-break: keep-all;
  line-height: 1.8;
}

/* ---------- 返回顶部 ---------- */
.back-top {
  position: fixed;
  right: 26px; bottom: 26px;
  z-index: 90;
  width: 46px; height: 46px;
  border: 0;
  border-radius: 50%;
  background: var(--c-primary);
  color: #fff;
  display: grid; place-items: center;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0;
  transform: translateY(16px);
  pointer-events: none;
  transition: opacity .4s var(--ease-out), transform .4s var(--ease-out), background .3s;
}
.back-top.show { opacity: 1; transform: none; pointer-events: auto; }
.back-top:hover { background: var(--c-primary-deep); }
.back-top svg { width: 20px; height: 20px; }

/* ==========================================================
   响应式：平板 ≤ 1024px
   ========================================================== */
@media (max-width: 1024px) {
  .section { padding: 84px 0; }

  .course-grid, .voice-grid, .camp-grid { grid-template-columns: repeat(2, 1fr); }
  .step-grid { grid-template-columns: repeat(2, 1fr); }
  .gallery { grid-template-columns: repeat(2, 1fr); }

  .split-inner { gap: 44px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

/* ==========================================================
   响应式：中屏及以下 ≤ 900px — 导航折叠为全屏抽屉
   ========================================================== */
@media (max-width: 900px) {
  .nav-toggle { display: flex; }
  .site-nav {
    position: fixed;
    inset: 0;
    z-index: -1;
    flex-direction: column;
    justify-content: center;
    gap: 30px;
    background: rgba(28, 39, 34, .97);
    color: #fff;
    font-size: 1.2rem;
    opacity: 0;
    pointer-events: none;
    transition: opacity .4s var(--ease-out);
  }
  .site-nav.open { opacity: 1; pointer-events: auto; z-index: 99; }
}

/* ==========================================================
   响应式：手机 ≤ 640px
   ========================================================== */
@media (max-width: 640px) {
  .container { width: calc(100% - 40px); }
  .section { padding: 68px 0; }
  .section-head { margin-bottom: 44px; }

  .hero-actions .btn { width: min(300px, 82vw); justify-content: center; }

  .stats { padding: 48px 0; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 26px; }

  .course-grid, .voice-grid, .camp-grid, .step-grid { grid-template-columns: 1fr; }
  .split-inner { grid-template-columns: 1fr; gap: 36px; }
  .split-reverse .split-media { order: 0; }

  .footer-grid { grid-template-columns: 1fr; gap: 28px; padding-bottom: 36px; }
  .site-footer { padding-top: 56px; }
  .footer-bottom {
    padding: 18px 0 86px;
    font-size: .85rem;
    line-height: 1.7;
  }
  .back-top { right: 18px; bottom: 18px; }
}