/* ============================================================
   小蚂蚁计算机科普教育基地 · 设计系统
   品牌：深海蓝 → 科技青 → 暖琥珀 （代码 · 科技 · 蚂蚁温度）
   ============================================================ */
:root {
  /* 色板 */
  --ink: #0B1F3A;
  --ink-2: #122a52;
  --ink-3: #1b3a6b;
  --blue: #2563EB;
  --blue-2: #1d4ed8;
  --cyan: #06B6D4;
  --amber: #F59E0B;
  --amber-2: #FBBF24;
  --emerald: #10B981;
  --violet: #8B5CF6;
  --rose: #F43F5E;

  --bg: #F6F8FC;
  --surface: #FFFFFF;
  --text: #0F172A;
  --muted: #64748B;
  --line: #E6EBF2;

  --grad-brand: linear-gradient(120deg, #2563EB 0%, #06B6D4 55%, #F59E0B 100%);
  --grad-ink: linear-gradient(160deg, #0B1F3A 0%, #122a52 60%, #1b3a6b 100%);
  --grad-soft: linear-gradient(120deg, rgba(37,99,235,.10), rgba(6,182,212,.10));
  --shadow-sm: 0 1px 2px rgba(11,31,58,.06), 0 4px 12px rgba(11,31,58,.05);
  --shadow-md: 0 6px 24px rgba(11,31,58,.10);
  --shadow-lg: 0 20px 50px rgba(11,31,58,.18);
  --shadow-glow: 0 10px 40px rgba(37,99,235,.35);

  --radius: 18px;
  --radius-sm: 12px;
  --radius-pill: 999px;
  --maxw: 1200px;
  --nav-h: 72px;

  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-display: "Noto Sans SC", "PingFang SC", system-ui, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

/* ---------- 布局 ---------- */
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.section { padding: 96px 0; position: relative; }
.section--tight { padding: 64px 0; }
.section--dark { background: var(--grad-ink); color: #E8EEF9; }
.section--dark .muted { color: #9FB0CC; }
.section--dark .card { background: rgba(255,255,255,.04); border-color: rgba(255,255,255,.08); }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 13px; font-weight: 700; letter-spacing: .14em; text-transform: uppercase;
  color: var(--blue); margin-bottom: 14px;
}
.eyebrow::before { content: ""; width: 28px; height: 2px; background: var(--grad-brand); border-radius: 2px; }
.section--dark .eyebrow { color: var(--cyan); }
.section-title {
  font-family: var(--font-display);
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 900; line-height: 1.2; letter-spacing: -.01em;
  margin-bottom: 14px;
}
.section-sub { font-size: 17px; color: var(--muted); max-width: 680px; }
.section--dark .section-sub { color: #B6C4DE; }
.grad-text {
  background: var(--grad-brand); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}

/* ---------- 顶部导航 ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.82); backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line);
  transition: box-shadow .3s;
}
.site-header.scrolled { box-shadow: var(--shadow-sm); }
.nav {
  height: var(--nav-h); display: flex; align-items: center; justify-content: space-between; gap: 24px;
}
.brand { display: flex; align-items: center; gap: 12px; font-weight: 900; }
.brand-logo {
  width: 42px; height: 42px; border-radius: 12px; background: var(--grad-brand);
  display: grid; place-items: center; color: #fff; font-size: 22px; font-weight: 900;
  box-shadow: var(--shadow-glow); flex-shrink: 0;
}
.brand-name { font-size: 17px; line-height: 1.15; color: var(--ink); }
.brand-name small { display: block; font-size: 11px; font-weight: 500; color: var(--muted); letter-spacing: .06em; }
.nav-menu { display: flex; align-items: center; gap: 4px; }
.nav-menu > li { position: relative; }
.nav-menu > li > a {
  display: block; padding: 10px 14px; font-size: 15px; font-weight: 600; color: #334155;
  border-radius: var(--radius-sm); transition: color .2s, background .2s;
}
.nav-menu > li > a:hover { color: var(--blue); background: var(--grad-soft); }
.nav-menu > li.active > a { color: var(--blue); }
.nav-menu > li.active > a::after {
  content: ""; display: block; height: 3px; width: 22px; margin: 4px auto 0;
  background: var(--grad-brand); border-radius: 3px;
}
/* 下拉 */
.nav-menu .sub {
  position: absolute; top: 100%; left: 50%; transform: translateX(-50%) translateY(8px);
  min-width: 180px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow-md); padding: 8px; opacity: 0; visibility: hidden; transition: .22s;
}
.nav-menu > li:hover .sub { opacity: 1; visibility: visible; transform: translateX(-50%) translateY(0); }
.nav-menu .sub a { display: block; padding: 10px 14px; font-size: 14px; color: #475569; border-radius: 10px; }
.nav-menu .sub a:hover { background: var(--grad-soft); color: var(--blue); }
.nav-cta {
  background: var(--grad-brand); color: #fff !important; padding: 10px 20px !important;
  border-radius: var(--radius-pill); font-weight: 700; box-shadow: var(--shadow-glow);
  transition: transform .2s;
}
.nav-cta:hover { transform: translateY(-2px); color: #fff !important; background: var(--grad-brand) !important; }
.nav-toggle { display: none; background: none; border: 0; font-size: 26px; color: var(--ink); cursor: pointer; }

/* ---------- Hero ---------- */
.hero {
  position: relative; overflow: hidden; background: var(--grad-ink);
  color: #fff; padding: 110px 0 130px;
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background:
    radial-gradient(600px 400px at 15% 20%, rgba(37,99,235,.45), transparent 60%),
    radial-gradient(500px 380px at 85% 30%, rgba(6,182,212,.38), transparent 60%),
    radial-gradient(700px 500px at 50% 100%, rgba(245,158,11,.22), transparent 60%);
  animation: aurora 14s ease-in-out infinite alternate;
}
.hero::after {
  content: ""; position: absolute; inset: 0;
  background-image: linear-gradient(rgba(255,255,255,.04) 1px, transparent 1px),
                    linear-gradient(90deg, rgba(255,255,255,.04) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(ellipse at center, #000 30%, transparent 75%);
}
@keyframes aurora { 0%{transform:translate3d(0,0,0) scale(1)} 100%{transform:translate3d(-3%,2%,0) scale(1.08)} }
.hero-inner { position: relative; z-index: 2; max-width: 820px; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px; padding: 8px 16px;
  border: 1px solid rgba(255,255,255,.18); border-radius: var(--radius-pill);
  background: rgba(255,255,255,.06); font-size: 13px; font-weight: 600; color: #D7E3F7;
  margin-bottom: 28px; backdrop-filter: blur(6px);
}
.hero-badge .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--amber-2); box-shadow: 0 0 0 4px rgba(245,158,11,.25); }
.hero-typed { font-size: clamp(15px,1.8vw,20px); font-weight: 700; color: #D7E3F7; margin-bottom: 18px; letter-spacing: .02em; }
.hero-typed .typewriter { background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.hero-typed .cursor { display: inline-block; color: var(--cyan); animation: blink 1s step-end infinite; margin-left: 2px; }
@keyframes blink { 50% { opacity: 0; } }
.hero h1 {
  font-size: clamp(38px, 6.2vw, 70px); font-weight: 900; line-height: 1.08; letter-spacing: -.02em;
  margin-bottom: 22px;
}
.hero h1 .grad-text { -webkit-text-fill-color: transparent; }
.hero p.lead { font-size: clamp(16px, 1.7vw, 19px); color: #C7D6EE; max-width: 640px; margin-bottom: 38px; }
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }
.hero-stats { display: flex; gap: 36px; margin-top: 56px; flex-wrap: wrap; }
.hero-stat .num { font-size: 34px; font-weight: 900; background: var(--grad-brand); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.hero-stat .label { font-size: 13px; color: #A9BADA; }

/* 浮动装饰 */
.float-code { position: absolute; z-index: 1; font-family: ui-monospace, Menlo, monospace; font-size: 13px; color: rgba(255,255,255,.18); white-space: pre; pointer-events: none; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 13px 26px;
  border-radius: var(--radius-pill); font-weight: 700; font-size: 15px; cursor: pointer;
  border: 1px solid transparent; transition: transform .2s, box-shadow .2s, background .2s;
  text-align: center;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: var(--grad-brand); color: #fff; box-shadow: var(--shadow-glow); }
.btn-ghost { background: rgba(255,255,255,.1); color: #fff; border-color: rgba(255,255,255,.25); backdrop-filter: blur(6px); }
.btn-ghost:hover { background: rgba(255,255,255,.18); }
.btn-outline { background: #fff; color: var(--ink); border-color: var(--line); box-shadow: var(--shadow-sm); }
.btn-outline:hover { border-color: var(--blue); color: var(--blue); }
.btn-lg { padding: 16px 34px; font-size: 16px; }

/* ---------- 通用卡片 ---------- */
.card {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px; box-shadow: var(--shadow-sm); transition: transform .25s, box-shadow .25s, border-color .25s;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: #c7d6f0; }
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-auto { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }

/* ---------- 首页：理念 ---------- */
.phil-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; margin-top: 50px; }
.phil-card { text-align: left; }
.phil-icon {
  width: 52px; height: 52px; border-radius: 14px; background: var(--grad-soft);
  display: grid; place-items: center; font-size: 24px; margin-bottom: 18px; color: var(--blue);
}
.phil-card h3 { font-size: 18px; font-weight: 800; margin-bottom: 8px; }
.phil-card p { font-size: 14px; color: var(--muted); }

/* ---------- 课程体系 ---------- */
.tracks { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; margin-top: 50px; }
.track {
  position: relative; overflow: hidden; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 30px; transition: transform .25s, box-shadow .25s;
}
.track::before {
  content: ""; position: absolute; inset: 0 0 auto 0; height: 4px; background: var(--track-color, var(--blue));
}
.track:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); }
.track-head { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 14px; }
.track-code {
  font-size: 12px; font-weight: 800; letter-spacing: .1em; color: var(--track-color, var(--blue));
  background: color-mix(in srgb, var(--track-color, var(--blue)) 12%, transparent);
  padding: 4px 10px; border-radius: 8px;
}
.track-age { font-size: 12px; color: var(--muted); font-weight: 600; }
.track h3 { font-size: 21px; font-weight: 800; margin-bottom: 4px; }
.track-en { font-size: 12px; color: var(--muted); letter-spacing: .06em; margin-bottom: 12px; }
.track-desc { font-size: 14px; color: #475569; margin-bottom: 16px; }
.track-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 14px; }
.tag { font-size: 12px; padding: 4px 10px; border-radius: 999px; background: var(--bg); color: #475569; border: 1px solid var(--line); }
.track-output { font-size: 13px; color: var(--muted); border-top: 1px dashed var(--line); padding-top: 12px; }
.track-output b { color: var(--ink); }
.track.amber { --track-color: var(--amber); }
.track.cyan { --track-color: var(--cyan); }
.track.blue { --track-color: var(--blue); }
.track.emerald { --track-color: var(--emerald); }
.track.violet { --track-color: var(--violet); }
.track.rose { --track-color: var(--rose); }

/* ---------- 师资卡片 ---------- */
.teacher-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; margin-top: 40px; }
.teacher {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; transition: transform .25s, box-shadow .25s; display: flex; flex-direction: column;
}
.teacher:hover { transform: translateY(-5px); box-shadow: var(--shadow-lg); }
.teacher-photo { aspect-ratio: 4/3; background: #E9EEF6; overflow: hidden; }
.teacher-photo img { width: 100%; height: 100%; object-fit: cover; transition: transform .5s; }
.teacher:hover .teacher-photo img { transform: scale(1.06); }
.teacher-photo .ph { width:100%;height:100%;display:grid;place-items:center;font-size:48px;color:#cbd5e1; }
.teacher-body { padding: 18px; flex: 1; }
.teacher-body h4 { font-size: 17px; font-weight: 800; }
.teacher-body .meta { font-size: 12px; color: var(--muted); margin-bottom: 8px; }
.teacher-body p { font-size: 13px; color: #475569; }

/* ---------- 数据统计带 ---------- */
.stats-band { background: var(--grad-ink); border-radius: var(--radius); padding: 48px; margin: 0 auto; position: relative; overflow: hidden; }
.stats-band::after { content:""; position:absolute; inset:0; background-image:linear-gradient(rgba(255,255,255,.04) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.04) 1px,transparent 1px); background-size:36px 36px; }
.stats-band .grid { position: relative; z-index: 2; }
.stat { text-align: center; color: #fff; }
.stat .num { font-size: clamp(34px,4vw,52px); font-weight: 900; background: var(--grad-brand); -webkit-background-clip:text; background-clip:text; -webkit-text-fill-color:transparent; line-height: 1; }
.stat .label { margin-top: 10px; font-size: 14px; color: #B6C4DE; }

/* ---------- 新闻列表 ---------- */
.news-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.news-item {
  display: flex; gap: 16px; padding: 18px; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); transition: all .2s;
}
.news-item:hover { border-color: var(--blue); box-shadow: var(--shadow-sm); transform: translateX(4px); }
.news-date { flex-shrink: 0; width: 64px; text-align: center; border-right: 1px solid var(--line); padding-right: 14px; }
.news-date .d { font-size: 22px; font-weight: 900; color: var(--blue); }
.news-date .m { font-size: 11px; color: var(--muted); }
.news-body h4 { font-size: 15px; font-weight: 700; margin-bottom: 6px; line-height: 1.4; }
.news-body p { font-size: 13px; color: var(--muted); }

/* ---------- 风采 / 画廊 ---------- */
.gallery { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin-top: 40px; }
.gallery-item {
  position: relative; aspect-ratio: 4/3; border-radius: var(--radius); overflow: hidden;
  background: #E9EEF6; cursor: pointer;
}
.gallery-item img { width: 100%; height: 100%; object-fit: cover; transition: transform .5s; }
.gallery-item:hover img { transform: scale(1.08); }
.gallery-item .cap {
  position: absolute; left: 0; right: 0; bottom: 0; padding: 24px 14px 12px;
  background: linear-gradient(transparent, rgba(11,31,58,.8)); color: #fff; font-size: 14px; font-weight: 600;
  transform: translateY(6px); opacity: 0; transition: .25s;
}
.gallery-item:hover .cap { transform: translateY(0); opacity: 1; }

/* ---------- 专利 ---------- */
.patent-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
.patent-item {
  display: flex; gap: 14px; padding: 18px; background: var(--surface); border: 1px solid var(--line);
  border-radius: var(--radius); border-left: 4px solid var(--blue); transition: all .2s;
}
.patent-item:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.patent-ic { width: 40px; height: 40px; flex-shrink: 0; border-radius: 10px; background: var(--grad-soft); display: grid; place-items: center; font-size: 18px; }
.patent-body h4 { font-size: 15px; font-weight: 700; margin-bottom: 4px; }
.patent-body .meta { font-size: 12px; color: var(--muted); }

/* ---------- 产品矩阵 ---------- */
.product-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 14px; margin-top: 40px; }
.product {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px;
  transition: all .2s; position: relative; overflow: hidden;
}
.product:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: var(--cyan); }
.product .tag { position: absolute; top: 12px; right: 12px; font-size: 11px; }
.product h4 { font-size: 16px; font-weight: 800; margin: 18px 0 6px; }
.product p { font-size: 13px; color: var(--muted); }

/* ---------- 流程时间线 ---------- */
.process { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin-top: 40px; }
.step { position: relative; padding: 26px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); }
.step .n { font-size: 40px; font-weight: 900; background: var(--grad-brand); -webkit-background-clip:text; background-clip:text; -webkit-text-fill-color:transparent; line-height: 1; }
.step h4 { font-size: 17px; font-weight: 800; margin: 8px 0; }
.step p { font-size: 13px; color: var(--muted); }

/* ---------- 组织架构 ---------- */
.org-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; margin-top: 40px; }
.org-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; border-top: 3px solid var(--blue); }
.org-card h4 { font-size: 18px; font-weight: 800; margin-bottom: 6px; }
.org-card .desc { font-size: 13px; color: var(--muted); margin-bottom: 12px; }
.org-card ul { display: flex; flex-wrap: wrap; gap: 8px; }
.org-card ul li { font-size: 13px; padding: 5px 12px; background: var(--bg); border-radius: 999px; color: #334155; border: 1px solid var(--line); }

/* ---------- 合作单位 ---------- */
.partner-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 40px; }
.partner { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; text-align: center; transition: all .2s; }
.partner:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); border-color: var(--cyan); }
.partner .logo-box { height: 48px; display: grid; place-items: center; font-size: 22px; font-weight: 900; color: var(--blue); margin-bottom: 10px; }
.partner h4 { font-size: 15px; font-weight: 800; margin-bottom: 4px; }
.partner p { font-size: 12px; color: var(--muted); }

/* ---------- CTA 带 ---------- */
.cta-band {
  background: var(--grad-ink); border-radius: var(--radius); padding: 56px; text-align: center; color: #fff;
  position: relative; overflow: hidden; margin: 0 auto;
}
.cta-band::before { content:""; position:absolute; inset:0; background: radial-gradient(400px 200px at 50% 0%, rgba(37,99,235,.4), transparent 70%); }
.cta-band > * { position: relative; z-index: 2; }
.cta-band h2 { font-size: clamp(26px, 3.4vw, 38px); font-weight: 900; margin-bottom: 12px; }
.cta-band p { color: #B6C4DE; margin-bottom: 28px; }

/* ---------- 页脚 ---------- */
.site-footer { background: #08152B; color: #C7D6EE; padding: 64px 0 28px; margin-top: 60px; }
.foot-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 40px; }
.site-footer .brand-name { color: #fff; }
.site-footer .brand-name small { color: #8AA0C2; }
.foot-about p { font-size: 13px; color: #8AA0C2; margin-top: 14px; line-height: 1.8; }
.foot-col h5 { font-size: 14px; font-weight: 800; color: #fff; margin-bottom: 16px; letter-spacing: .04em; }
.foot-col ul li { margin-bottom: 10px; }
.foot-col ul li a { font-size: 13px; color: #8AA0C2; transition: color .2s; }
.foot-col ul li a:hover { color: var(--cyan); }
.foot-contact p { font-size: 13px; color: #8AA0C2; margin-bottom: 8px; }
.foot-bottom { border-top: 1px solid rgba(255,255,255,.08); margin-top: 44px; padding-top: 22px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; font-size: 12px; color: #6B7FA3; }
.foot-bottom a { color: #8AA0C2; }

/* ---------- 表单 ---------- */
.form-wrap { max-width: 640px; margin: 0 auto; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 40px; box-shadow: var(--shadow-md); }
.field { margin-bottom: 20px; }
.field label { display: block; font-size: 14px; font-weight: 700; margin-bottom: 8px; color: #334155; }
.field label .req { color: var(--rose); }
.field input, .field textarea, .field select {
  width: 100%; padding: 13px 16px; border: 1px solid var(--line); border-radius: var(--radius-sm);
  font-size: 15px; font-family: inherit; background: #FAFBFD; transition: border-color .2s, box-shadow .2s;
}
.field input:focus, .field textarea:focus, .field select:focus {
  outline: none; border-color: var(--blue); box-shadow: 0 0 0 4px rgba(37,99,235,.12); background: #fff;
}
.field textarea { resize: vertical; min-height: 120px; }
.form-grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }

/* ---------- 页面标题区（内页） ---------- */
.page-hero {
  background: var(--grad-ink); color: #fff; padding: 72px 0 64px; position: relative; overflow: hidden;
}
.page-hero::before { content:""; position:absolute; inset:0; background: radial-gradient(600px 300px at 20% 0%, rgba(37,99,235,.4), transparent 60%), radial-gradient(500px 300px at 90% 100%, rgba(6,182,212,.3), transparent 60%); }
.page-hero .container { position: relative; z-index: 2; }
.crumb { font-size: 13px; color: #9FB0CC; margin-bottom: 14px; }
.crumb a:hover { color: var(--cyan); }
.crumb .sep { margin: 0 8px; opacity: .5; }
.page-hero h1 { font-size: clamp(30px, 4.4vw, 48px); font-weight: 900; }
.page-hero p { color: #C7D6EE; margin-top: 12px; max-width: 640px; }

/* ---------- 工具 / 动画 ---------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }
.text-center { text-align: center; }
.mt-0 { margin-top: 0; } .mt-8 { margin-top: 8px; } .mt-16 { margin-top: 16px; } .mt-24 { margin-top: 24px; } .mt-40 { margin-top: 40px; } .mt-60 { margin-top: 60px; }
.flex { display: flex; } .flex-wrap { flex-wrap: wrap; } .items-center { align-items: center; } .justify-between { justify-content: space-between; } .gap-12{gap:12px} .gap-16{gap:16px}
.muted { color: var(--muted); }
.badge-cat { display:inline-block; font-size:12px; font-weight:700; padding:4px 10px; border-radius:999px; background: var(--grad-soft); color: var(--blue); }
.empty-hint { text-align:center; padding:60px 20px; color:var(--muted); }

/* back to top */
.to-top {
  position: fixed; right: 24px; bottom: 24px; width: 48px; height: 48px; border-radius: 50%;
  background: var(--grad-brand); color: #fff; border: 0; cursor: pointer; font-size: 20px;
  box-shadow: var(--shadow-glow); opacity: 0; visibility: hidden; transition: .3s; z-index: 90;
}
.to-top.show { opacity: 1; visibility: visible; }
.to-top:hover { transform: translateY(-3px); }

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .tracks, .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .phil-grid { grid-template-columns: repeat(2, 1fr); }
  .teacher-grid { grid-template-columns: repeat(3, 1fr); }
  .gallery, .product-grid { grid-template-columns: repeat(3, 1fr); }
  .foot-grid { grid-template-columns: 1fr 1fr; }
  .partner-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 820px) {
  .nav-toggle { display: block; }
  .nav-menu {
    position: absolute; top: var(--nav-h); left: 0; right: 0; flex-direction: column; align-items: stretch;
    background: #fff; border-bottom: 1px solid var(--line); padding: 12px; gap: 2px;
    max-height: 0; overflow: hidden; transition: max-height .3s; box-shadow: var(--shadow-md);
  }
  .nav-menu.open { max-height: 70vh; overflow-y: auto; }
  .nav-menu .sub { position: static; transform: none; opacity: 1; visibility: visible; box-shadow: none; border: 0; padding-left: 12px; }
  .hero { padding: 70px 0 90px; }
  .section { padding: 64px 0; }
  .tracks, .grid-2, .grid-3, .grid-4, .news-list, .patent-list, .process, .org-grid { grid-template-columns: 1fr; }
  .teacher-grid { grid-template-columns: repeat(2, 1fr); }
  .gallery { grid-template-columns: repeat(2, 1fr); }
  .product-grid { grid-template-columns: repeat(2, 1fr); }
  .phil-grid { grid-template-columns: 1fr 1fr; }
  .partner-grid { grid-template-columns: repeat(2, 1fr); }
  .foot-grid { grid-template-columns: 1fr; gap: 28px; }
  .form-grid-2 { grid-template-columns: 1fr; }
  .stats-band, .cta-band { padding: 32px 22px; }
}
@media (max-width: 480px) {
  .teacher-grid, .gallery, .product-grid, .phil-grid, .partner-grid { grid-template-columns: 1fr; }
  .hero-stats { gap: 20px; }
}