/* ==========================================================================
   Monster Science 官网样式表
   设计令牌与首屏尺寸严格依据《需求与技术文档 v1.2》4.2 / 4.3 / 4.4 / 4.7
   唯一页面底色：纯白 #FFFFFF
   ========================================================================== */

:root {
  /* 品牌色（取色自 Logo，禁止偏色） */
  --navy: #1f3b5e;
  --yellow: #fabd1d;
  --blue: #24b6e4;
  --brown: #996f56;
  --red: #e7333b;

  /* 界面色 */
  --bg: #ffffff;
  --text: #333333;
  --muted: #666666;
  --weak: #8a8a8a;
  --line: #e6e6e6;

  /* 尺寸令牌（4.7） */
  --nav-h: 80px;
  --logo-h: 46px;
  --page-x: 96px;
  --hero-h: 496px;
  --stats-h: 104px;
  --radius: 6px;
  --sec-y: 48px; /* 区块间合计 96px 留白：48 下 + 48 上，见 6.1 整页视觉约束 */
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; }

/* --------------------------------------------------------------------------
   导航
   -------------------------------------------------------------------------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 20;
  height: var(--nav-h);
  background: #fff;
  border-bottom: 1px solid var(--line);
  transition: box-shadow .2s ease;
}
.nav.scrolled { box-shadow: 0 1px 12px rgba(31, 59, 94, .08); }

.nav-inner {
  height: 100%;
  padding: 0 var(--page-x);
  display: flex;
  align-items: center;
  gap: 40px;
}

.nav-logo { display: flex; align-items: center; height: var(--logo-h); flex: none; }
.nav-logo img { height: var(--logo-h); width: auto; }

.nav-menu { display: flex; align-items: center; gap: 40px; margin-left: 8px; }
.nav-link {
  font-size: 15px;
  color: var(--text);
  position: relative;
  padding: 6px 0;
  white-space: nowrap;
}
.nav-link::after {
  content: "";
  position: absolute; left: 0; right: 0; bottom: 0;
  height: 2px; background: var(--navy);
  transform: scaleX(0);
  transition: transform .18s ease;
}
.nav-link:hover::after,
.nav-link.active::after { transform: scaleX(1); }

.nav-right { margin-left: auto; display: flex; align-items: center; gap: 16px; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 48px;
  padding: 0 28px;
  font-size: 16px;
  font-weight: 600;
  border-radius: var(--radius);
  border: 0;
  transition: background .16s ease, color .16s ease, border-color .16s ease, transform .16s ease;
  white-space: nowrap;
}
/* 黄底必须配藏青字（6.7:1）；蓝底必须配藏青字（4.82:1）——禁止白字 */
.btn-yellow { background: var(--yellow); color: var(--navy); }
.btn-yellow:hover { background: #f5b208; }
.btn-outline {
  background: #fff;
  color: var(--navy);
  border: 2px solid var(--navy);
}
.btn-outline:hover { background: var(--navy); color: #fff; }
.btn-nav { height: 40px; padding: 0 20px; font-size: 15px; }
.btn-lg { height: 52px; padding: 0 32px; font-size: 16px; }

.nav-burger {
  display: none;
  width: 32px; height: 32px;
  background: none; border: 0; padding: 0;
  flex-direction: column; justify-content: center; gap: 5px;
}
.nav-burger span { display: block; height: 2px; background: var(--navy); }

/* --------------------------------------------------------------------------
   首屏（4.7 像素规格）
   -------------------------------------------------------------------------- */
.hero {
  display: grid;
  grid-template-columns: 46% 54%;
  height: var(--hero-h);
  overflow: hidden;
}

.hero-left {
  padding-left: var(--page-x);
  padding-right: 24px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
}

/* 小标签：天蓝底 + 藏青字 */
.tag-blue {
  display: inline-flex;
  align-items: center;
  height: 34px;
  padding: 0 14px;
  background: var(--blue);
  color: var(--navy);
  font-size: 14px;
  font-weight: 500;
  border-radius: var(--radius);
}

/* H1：64px / 1.15 / 700 / 藏青；两行断行位置写死 */
.hero-title {
  margin: 20px 0 0;
  font-size: 64px;
  line-height: 1.15;
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--navy);
}

/* 副标：24px / 1.5 / 400 / #666 */
.hero-sub {
  margin: 28px 0 0;
  font-size: 24px;
  line-height: 1.5;
  color: var(--muted);
}

/* STEM 四要素行：14px，中文 500 #5A5A5A，英文 400 #8A8A8A 全大写 ls .08em */
.stem-row {
  margin-top: 20px;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  flex-wrap: nowrap;
}
.stem-item { font-size: 14px; font-weight: 500; color: #5a5a5a; white-space: nowrap; }
.stem-item em {
  font-style: normal;
  font-weight: 400;
  color: var(--weak);
  text-transform: uppercase;
  letter-spacing: .06em;
  font-size: 12px;
  margin-left: 2px;
}
.stem-sep { width: 1px; height: 14px; background: #ccc; }

.hero-actions { margin-top: 32px; display: flex; gap: 12px; }

.hero-right { position: relative; overflow: hidden; }
.hero-right img { width: 100%; height: 100%; object-fit: cover; }

/* --------------------------------------------------------------------------
   数据带：藏青通栏 104px，5 组
   -------------------------------------------------------------------------- */
.stats-band { background: var(--navy); height: var(--stats-h); }
.stats-inner {
  height: 100%;
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 64px;
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  align-items: center;
}
.stat { text-align: center; border-left: 1px solid rgba(255, 255, 255, .18); }
.stat:first-child { border-left: 0; }
.stat-value {
  font-size: 36px;
  font-weight: 700;
  line-height: 1.1;
  color: #fff;
  font-variant-numeric: tabular-nums;
}
.stat-label { margin-top: 6px; font-size: 14px; color: rgba(255, 255, 255, .72); }

/* --------------------------------------------------------------------------
   合作学校条
   -------------------------------------------------------------------------- */
.schools-strip { padding: 40px 0; border-bottom: 1px solid var(--line); }
.schools-inner {
  max-width: 1248px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 40px;
}
.schools-label { font-size: 14px; color: var(--muted); flex: none; }
.schools-logos { display: flex; gap: 24px; flex-wrap: wrap; }
.school-logo {
  width: 96px; height: 40px;
  display: grid; place-items: center;
  border: 1px solid var(--line);
  border-radius: 4px;
  font-size: 11px;
  letter-spacing: .12em;
  color: #bfbfbf;
  filter: grayscale(1);
  transition: filter .2s ease, border-color .2s ease;
}
.school-logo:hover { filter: none; border-color: #cfcfcf; }

/* --------------------------------------------------------------------------
   通用区块
   -------------------------------------------------------------------------- */
.sec { padding: var(--sec-y) 0; }
.sec-tint { background: #fafbfc; }
.sec-inner { max-width: 1248px; margin: 0 auto; padding: 0 24px; }

.sec-head { max-width: 760px; margin-bottom: 48px; }
.sec-title {
  margin: 0;
  font-size: 40px;
  line-height: 1.25;
  font-weight: 700;
  color: var(--navy);
  letter-spacing: -.01em;
}
.sec-desc { margin: 16px 0 0; font-size: 16px; line-height: 1.75; color: var(--muted); }

.sec-more { margin-top: 40px; }
.link-arrow { font-size: 15px; font-weight: 600; color: var(--navy); }
.link-arrow::after { content: " →"; }

.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }

/* 卡片：白底 + 1px #E6E6E6 + 6px 圆角 */
.card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 32px;
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}
.card:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(31, 59, 94, .07); }
.card-title { margin: 0; font-size: 22px; font-weight: 700; color: var(--navy); line-height: 1.35; }
.card-en {
  font-size: 12px; font-weight: 400; color: var(--weak);
  text-transform: uppercase; letter-spacing: .08em;
}
.card-desc { margin: 12px 0 0; font-size: 15px; line-height: 1.75; color: var(--muted); }

/* STEM 四域 */
.stem-icon {
  width: 56px; height: 56px;
  border-radius: var(--radius);
  display: grid; place-items: center;
  color: var(--navy);
  margin-bottom: 24px;
}
.stem-icon svg { width: 30px; height: 30px; }
.accent-yellow { background: rgba(250, 189, 29, .14); }
.accent-blue { background: rgba(36, 182, 228, .14); }
.accent-navy { background: rgba(31, 59, 94, .10); }
.accent-brown { background: rgba(153, 111, 86, .14); }

/* 三级体系：以尺寸递进表达成长，不用卡通角色 */
.level-card { padding: 40px 32px; }
.level-dot {
  border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, rgba(250,189,29,.22), rgba(31,59,94,.10) 70%);
  border: 1px solid rgba(31, 59, 94, .18);
  margin-bottom: 28px;
}
.level-age { font-size: 14px; font-weight: 600; color: var(--blue); margin-left: 8px; }
.level-system { margin: 8px 0 0; font-size: 13px; color: var(--weak); }

/* 三大业务 */
.biz-card { display: block; }
.biz-icon { width: 44px; height: 44px; color: var(--navy); margin-bottom: 24px; }
.biz-icon svg { width: 36px; height: 36px; }
.biz-card .link-arrow { display: inline-block; margin-top: 20px; }

/* 课题卡 */
.topic-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: #fff;
  transition: transform .18s ease, box-shadow .18s ease;
}
.topic-card:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(31, 59, 94, .07); }
.topic-thumb {
  height: 180px;
  background:
    radial-gradient(120% 90% at 20% 15%, rgba(36, 182, 228, .20) 0%, rgba(36, 182, 228, 0) 60%),
    linear-gradient(135deg, #f2f6fa 0%, #e8eff6 100%);
  display: grid;
  place-items: center;
  position: relative;
}
.topic-thumb span {
  font-size: 13px; letter-spacing: .12em; color: #9aa7b6;
  text-transform: uppercase;
}
.topic-body { padding: 20px 24px 24px; }
.topic-title { margin: 0; font-size: 20px; font-weight: 700; color: var(--navy); }
.topic-meta { margin-top: 12px; display: flex; gap: 8px; }
.chip {
  font-size: 12px;
  padding: 3px 10px;
  border-radius: 4px;
  background: rgba(36, 182, 228, .12);
  color: var(--navy);
}
.chip-ghost { font-size: 12px; padding: 3px 10px; border-radius: 4px; border: 1px solid var(--line); color: var(--muted); }

/* 活动 */
.act-card, .case-card { padding: 0; overflow: hidden; }
.act-thumb, .case-thumb {
  height: 160px;
  background: linear-gradient(135deg, #1f3b5e 0%, #2c527c 100%);
  position: relative;
}
.act-thumb::after, .case-thumb::after {
  content: "";
  position: absolute; inset: 0;
  background: radial-gradient(80% 60% at 70% 30%, rgba(250, 189, 29, .28), transparent 70%);
}
.act-body, .case-body { padding: 24px; }
.act-meta { margin: 10px 0 0; font-size: 13px; color: var(--weak); }

/* 师资 */
.teachers-row { display: grid; grid-template-columns: repeat(5, 1fr); gap: 20px; }
.teacher-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 32px 20px;
  text-align: center;
  background: #fff;
}
.teacher-avatar {
  width: 64px; height: 64px;
  margin: 0 auto 18px;
  border-radius: 50%;
  background: var(--navy);
  color: #fff;
  font-size: 20px; font-weight: 700;
  display: grid; place-items: center;
}
.teacher-name { margin: 0; font-size: 17px; font-weight: 700; color: var(--navy); }
.teacher-role { margin: 6px 0 0; font-size: 13px; color: var(--blue); }
.teacher-note { margin: 8px 0 0; font-size: 13px; color: var(--muted); line-height: 1.6; }

/* 证言 */
.quotes { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.quote-card { margin: 0; padding: 8px 0 8px 24px; border-left: 3px solid var(--navy); }
.quote-text { margin: 0; font-size: 20px; line-height: 1.7; color: var(--text); }
.quote-from { display: block; margin-top: 14px; font-size: 14px; font-style: normal; color: var(--weak); }

/* CTA 横幅 */
.cta-band { background: var(--navy); padding: 72px 0; }
.cta-inner {
  max-width: 1248px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 48px;
}
.cta-title { margin: 0; font-size: 36px; line-height: 1.3; font-weight: 700; color: #fff; }
.cta-desc { margin: 14px 0 0; font-size: 16px; color: rgba(255, 255, 255, .72); }

/* --------------------------------------------------------------------------
   页脚
   -------------------------------------------------------------------------- */
.footer { background: var(--navy); color: rgba(255, 255, 255, .72); padding: 64px 0 0; }
.footer-inner {
  max-width: 1248px; margin: 0 auto; padding: 0 24px;
  display: grid; grid-template-columns: 1.2fr 1.6fr; gap: 64px;
}
.footer-name { font-size: 22px; font-weight: 700; color: #fff; }
.footer-name span { font-size: 13px; font-weight: 400; letter-spacing: .08em; color: rgba(255, 255, 255, .6); text-transform: uppercase; }
.footer-slogan { margin: 14px 0 0; font-size: 15px; line-height: 1.7; max-width: 380px; }
.footer-corp { margin: 12px 0 0; font-size: 13px; color: rgba(255, 255, 255, .55); }
.footer-links { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
.footer-col h4 { margin: 0 0 16px; font-size: 14px; font-weight: 600; color: #fff; }
.footer-col a { display: block; font-size: 14px; line-height: 2.1; color: rgba(255, 255, 255, .72); }
.footer-col a:hover { color: var(--yellow); }
.footer-bottom {
  max-width: 1248px; margin: 48px auto 0; padding: 24px;
  border-top: 1px solid rgba(255, 255, 255, .15);
  display: flex; justify-content: space-between;
  font-size: 13px; color: rgba(255, 255, 255, .55);
}
.footer-legal a { color: rgba(255, 255, 255, .55); }

/* --------------------------------------------------------------------------
   内页通用
   -------------------------------------------------------------------------- */
.page-head { padding: 64px 0 48px; border-bottom: 1px solid var(--line); }
.crumb { margin: 0 0 20px; font-size: 13px; color: var(--weak); }
.crumb a { color: var(--weak); }
.page-title { margin: 0; font-size: 44px; line-height: 1.2; font-weight: 700; color: var(--navy); letter-spacing: -.01em; }
.page-desc { margin: 20px 0 0; max-width: 780px; font-size: 16px; line-height: 1.75; color: var(--muted); }
.prose { font-size: 16px; line-height: 1.85; color: var(--muted); max-width: 640px; }
.milestones { list-style: none; margin: 0; padding: 0; }
.milestones li { padding: 14px 0; border-bottom: 1px solid var(--line); font-size: 15px; color: var(--text); }
.milestones li span { display: inline-block; width: 96px; font-weight: 700; color: var(--navy); }
.note { margin-top: 32px; font-size: 13px; color: var(--weak); }
.filters { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 32px; }

/* 时间线 */
.timeline { border-left: 1px solid var(--line); padding-left: 0; }
.tl-item { display: grid; grid-template-columns: 140px 1fr; gap: 24px; padding: 24px 0 24px 24px; border-bottom: 1px solid var(--line); }
.tl-date { font-size: 14px; color: var(--weak); }

/* 表单 */
.contact-wrap { display: grid; grid-template-columns: 1.6fr 1fr; gap: 64px; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.field { display: block; margin-bottom: 20px; }
.field-label { display: block; margin-bottom: 8px; font-size: 14px; font-weight: 600; color: var(--text); }
.field input, .field select, .field textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 13px 14px;
  font-size: 15px;
  font-family: inherit;
  color: var(--text);
  background: #fff;
  outline: none;
  transition: border-color .16s ease;
}
.field input:focus, .field select:focus, .field textarea:focus { border-color: var(--navy); }
.field textarea { resize: vertical; min-height: 120px; line-height: 1.6; }
.form-hint { margin: 16px 0 0; font-size: 12px; color: var(--weak); }
.alert { padding: 14px 16px; border-radius: var(--radius); font-size: 14px; margin-bottom: 24px; }
.alert-ok { background: rgba(36, 182, 228, .12); color: var(--navy); }
.alert-err { background: rgba(231, 51, 59, .10); color: #a3242b; }
.contact-aside { border-left: 1px solid var(--line); padding-left: 40px; }
.contact-line { margin: 12px 0 0; font-size: 15px; color: var(--muted); }
.contact-line a { color: var(--navy); font-weight: 600; }

/* --------------------------------------------------------------------------
   响应式（4.7 断点：≤1024 / ≤768）
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
  :root { --page-x: 32px; --hero-h: auto; }

  .nav-inner { gap: 20px; }
  .nav-menu { display: none; }
  .nav-burger { display: flex; }

  .hero { grid-template-columns: 1fr; height: auto; }
  .hero-left { padding: var(--page-x); order: 2; }
  .hero-right { order: 1; height: 320px; }
  .hero-title { font-size: 44px; }

  .stats-inner { grid-template-columns: repeat(3, 1fr); row-gap: 24px; height: auto; padding: 24px; }
  .stats-band { height: auto; }

  .grid-4, .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .teachers-row { grid-template-columns: repeat(3, 1fr); }
  .grid-2, .quotes, .contact-wrap { grid-template-columns: 1fr; gap: 32px; }
  .contact-aside { border-left: 0; padding-left: 0; border-top: 1px solid var(--line); padding-top: 32px; }
  .sec-title { font-size: 30px; }
  .cta-inner { flex-direction: column; align-items: flex-start; }
  .footer-inner { grid-template-columns: 1fr; gap: 40px; }
  .footer-links { grid-template-columns: repeat(3, 1fr); }
  .nav.scrolled { box-shadow: 0 1px 12px rgba(31, 59, 94, .08); }
}

@media (max-width: 768px) {
  :root { --page-x: 20px; --nav-h: 64px; --logo-h: 36px; }

  .hero-title { font-size: 32px; }
  .hero-sub { font-size: 18px; }
  .hero-right { height: 240px; }
  .hero-actions { flex-direction: column; align-items: stretch; width: 100%; }
  .hero-actions .btn { width: 100%; }

  .stats-inner { grid-template-columns: repeat(2, 1fr); }
  .grid-4, .grid-3 { grid-template-columns: 1fr; }
  .teachers-row { grid-template-columns: repeat(2, 1fr); }
  .form-row { grid-template-columns: 1fr; }
  .footer-links { grid-template-columns: 1fr 1fr; }
  .footer-bottom { flex-direction: column; gap: 8px; }
  .page-title { font-size: 32px; }
  .sec { padding: 56px 0; }
}