/* ============================================================
   同城学伴 · 首页（国际化视觉改版）
   风格：国际 SaaS  Landing —— 大字排版 / 英文眉题 / 留白 / 微交互
   配色：深松绿 + 暖纸白 + 珊瑚橙
   ============================================================ */
:root{
  --bg:#FAF9F5;
  --bg-soft:#F4F2EA;
  --card:#FFFFFF;
  --ink:#132019;
  --ink-2:#3C4C44;
  --muted:#75827B;
  --line:#E8E4D8;
  --brand:#0E7C5F;
  --brand-deep:#0A3B2B;
  --brand-soft:#E4F2EB;
  --accent:#FF7A59;
  --accent-soft:#FFE8E0;
  --gold:#F2B93B;
  --radius:22px;
  --shadow-sm:0 1px 2px rgba(19,32,25,.05),0 10px 28px rgba(19,32,25,.07);
  --shadow-lg:0 30px 70px rgba(10,59,43,.16);
  --font:"Inter","SF Pro Text","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:var(--font);
  color:var(--ink);background:var(--bg);line-height:1.65;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
a{text-decoration:none;color:inherit}
img{max-width:100%;display:block}
::selection{background:var(--brand);color:#fff}
.wrap{width:min(1160px,92vw);margin:0 auto}
section{scroll-margin-top:90px}

/* ---------- 按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  padding:12px 26px;border-radius:999px;font-weight:600;font-size:15px;
  border:none;cursor:pointer;transition:transform .2s ease,box-shadow .2s ease,background .2s ease,color .2s ease;
  white-space:nowrap;
}
.btn svg{width:16px;height:16px;flex-shrink:0}
.btn:hover{transform:translateY(-2px)}
.btn:active{transform:translateY(0)}
.btn-primary{background:var(--brand);color:#fff;box-shadow:0 10px 26px rgba(14,124,95,.32)}
.btn-primary:hover{background:#0B6C52;box-shadow:0 14px 32px rgba(14,124,95,.38)}
.btn-outline{background:#fff;color:var(--brand-deep);border:1.5px solid var(--brand)}
.btn-outline:hover{background:var(--brand-soft)}
.btn-dark{background:var(--brand-deep);color:#fff}
.btn-dark:hover{background:#0f4a37}
.btn-accent{background:var(--accent);color:#fff;box-shadow:0 10px 26px rgba(255,122,89,.35)}
.btn-accent:hover{background:#f96a47}
.btn-ghost{background:transparent;color:var(--ink-2);border:1.5px solid var(--line)}
.btn-ghost:hover{border-color:var(--brand);color:var(--brand-deep)}
.btn-sm{padding:8px 18px;font-size:13.5px}
.btn-lg{padding:15px 32px;font-size:16px}

/* ---------- 顶部导航 ---------- */
.site-head{
  position:fixed;top:0;left:0;right:0;z-index:100;
  transition:background .3s ease,box-shadow .3s ease,backdrop-filter .3s ease;
}
.site-head .head-wrap{display:flex;align-items:center;justify-content:space-between;height:76px;transition:height .3s ease}
.site-head.scrolled{background:rgba(250,249,245,.86);backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);
  box-shadow:0 1px 0 var(--line),0 12px 32px rgba(19,32,25,.06)}
.site-head.scrolled .head-wrap{height:64px}
.logo{display:flex;align-items:center;gap:11px;font-weight:800;font-size:20px;color:var(--brand-deep);letter-spacing:.5px}
.logo-mark{
  width:36px;height:36px;border-radius:12px;display:grid;place-items:center;color:#fff;font-size:15px;font-weight:800;
  background:linear-gradient(135deg,var(--brand),#0AA078);box-shadow:0 6px 16px rgba(14,124,95,.35);
  transition:transform .3s ease;
}
.logo:hover .logo-mark{transform:rotate(-8deg) scale(1.05)}
.logo-text{display:flex;flex-direction:column;line-height:1.05}
.logo-text em{font-style:normal;font-size:10px;font-weight:700;letter-spacing:3px;color:var(--muted)}
.nav-links{display:flex;gap:30px;font-size:14.5px;font-weight:500;color:var(--ink-2)}
.nav-links a{position:relative;padding:4px 0;transition:color .2s}
.nav-links a::after{content:"";position:absolute;left:0;right:100%;bottom:0;height:2px;border-radius:2px;
  background:var(--brand);transition:right .25s ease}
.nav-links a:hover{color:var(--brand-deep)}
.nav-links a:hover::after{right:0}
.nav-links a.nav-ai{color:var(--accent);font-weight:700}
.nav-links a.nav-ai::after{background:var(--accent)}
.head-cta{display:flex;gap:10px;align-items:center}
.burger{display:none;flex-direction:column;gap:5px;background:none;border:none;cursor:pointer;padding:8px}
.burger span{width:22px;height:2px;border-radius:2px;background:var(--ink);transition:.25s}
.site-head.open .burger span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.site-head.open .burger span:nth-child(2){opacity:0}
.site-head.open .burger span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}

/* ---------- Hero ---------- */
.hero{position:relative;padding:168px 0 90px;overflow:hidden}
.hero-bg{position:absolute;inset:0;pointer-events:none}
.hero-bg .blob{position:absolute;border-radius:50%;filter:blur(70px);opacity:.55}
.hero-bg .b1{width:520px;height:520px;right:-140px;top:-120px;
  background:radial-gradient(circle,rgba(14,160,120,.35),transparent 65%)}
.hero-bg .b2{width:420px;height:420px;left:-160px;bottom:-180px;
  background:radial-gradient(circle,rgba(255,150,110,.22),transparent 65%)}
.hero-bg .dots{position:absolute;inset:0;
  background-image:radial-gradient(rgba(14,124,95,.16) 1.2px,transparent 1.2px);
  background-size:24px 24px;
  -webkit-mask-image:radial-gradient(ellipse 70% 60% at 50% 40%,#000 30%,transparent 75%);
  mask-image:radial-gradient(ellipse 70% 60% at 50% 40%,#000 30%,transparent 75%);}
.hero-grid{display:grid;grid-template-columns:1.08fr .92fr;gap:56px;align-items:center;position:relative}

.eyebrow{display:inline-flex;align-items:center;gap:10px;font-size:12px;font-weight:700;
  letter-spacing:.22em;color:var(--brand);text-transform:uppercase;margin-bottom:18px}
.eyebrow-line{width:34px;height:2px;border-radius:2px;background:var(--brand)}
.hero h1{
  font-size:clamp(38px,4.6vw,60px);line-height:1.16;font-weight:800;letter-spacing:.01em;
  color:var(--brand-deep);
}
.hero h1 .hl{position:relative;color:var(--brand);white-space:nowrap}
.hero h1 .hl::after{
  content:"";position:absolute;left:-2%;right:-2%;bottom:6%;height:.34em;z-index:-1;border-radius:6px;
  background:linear-gradient(90deg,rgba(255,196,120,.55),rgba(255,150,110,.45));
}
.hero .lead{margin:22px 0 34px;font-size:18px;line-height:1.8;color:var(--ink-2);max-width:500px}
.hero .cta{display:flex;gap:14px;flex-wrap:wrap}
.trust{display:flex;align-items:center;gap:14px;margin-top:38px}
.faces{display:flex}
.faces i{
  width:38px;height:38px;border-radius:50%;display:grid;place-items:center;color:#fff;font-style:normal;
  font-size:13px;font-weight:700;border:2.5px solid var(--bg);margin-left:-10px;
}
.faces i:first-child{margin-left:0}
.faces i:nth-child(1){background:linear-gradient(135deg,#0E7C5F,#0AA078)}
.faces i:nth-child(2){background:linear-gradient(135deg,#E8930C,#F2B93B)}
.faces i:nth-child(3){background:linear-gradient(135deg,#4A7DD9,#6EA0FF)}
.faces i:nth-child(4){background:linear-gradient(135deg,#FF7A59,#FFA08A)}
.faces i:nth-child(5){background:linear-gradient(135deg,#7C5CD6,#A78BFA)}
.trust-txt{font-size:13.5px;color:var(--muted);line-height:1.5}
.trust-txt b{color:var(--ink);font-size:14px}
.stars{color:var(--gold);letter-spacing:2px;font-size:13px}
.stars em{font-style:normal;color:var(--muted);letter-spacing:0;margin-left:4px}

/* Hero 右侧产品 mock 卡 */
.hero-visual{position:relative}
.lesson-card{
  background:rgba(255,255,255,.92);backdrop-filter:blur(8px);
  border:1px solid rgba(232,228,216,.9);border-radius:26px;padding:24px;
  box-shadow:var(--shadow-lg);
  animation:floaty 6s ease-in-out infinite;
}
@keyframes floaty{0%,100%{transform:translateY(0)}50%{transform:translateY(-12px)}}
.lc-head{display:flex;align-items:center;gap:13px}
/* 头像图片填充（teacher_avatar() 输出）：继承容器圆角与尺寸 */
.av-img{width:100%;height:100%;object-fit:cover;display:block;border-radius:inherit}
.av-char{font-weight:800}
.lc-av{width:52px;height:52px;border-radius:16px;display:grid;place-items:center;color:#fff;font-weight:800;font-size:19px;
  background:linear-gradient(135deg,var(--brand),#0AA078)}
.lc-name{font-weight:700;font-size:15.5px;display:flex;align-items:center;gap:7px}
.lc-name .verified{display:inline-flex;align-items:center;gap:3px;font-size:11px;font-weight:600;color:var(--brand);
  background:var(--brand-soft);border-radius:999px;padding:2px 9px}
.lc-meta{font-size:12.5px;color:var(--muted);margin-top:2px}
.lc-price{margin-left:auto;text-align:right;font-weight:800;color:var(--accent);font-size:19px}
.lc-price small{display:block;font-size:11px;color:var(--muted);font-weight:500}
.lc-slots{display:flex;gap:8px;margin:16px 0 14px;flex-wrap:wrap}
.slot{font-size:12.5px;font-weight:600;padding:7px 13px;border-radius:10px;border:1.5px solid var(--line);
  color:var(--ink-2);background:#fff;transition:.2s}
.slot.on{background:var(--brand);border-color:var(--brand);color:#fff;box-shadow:0 6px 14px rgba(14,124,95,.28)}
.lc-foot{display:flex;align-items:center;justify-content:space-between;gap:10px;font-size:12.5px;
  color:var(--ink-2);padding-top:14px;border-top:1px dashed var(--line);flex-wrap:wrap}
.lc-foot .safe{display:inline-flex;align-items:center;gap:5px;color:var(--brand);font-weight:600}
.float-chip{
  position:absolute;background:#fff;border-radius:16px;padding:12px 16px;box-shadow:var(--shadow-sm);
  border:1px solid var(--line);font-size:12.5px;font-weight:600;display:flex;align-items:center;gap:9px;
  animation:floaty 5s ease-in-out infinite;
}
.float-chip .fico{width:32px;height:32px;border-radius:10px;display:grid;place-items:center;font-size:15px}
.float-chip small{display:block;font-size:11px;color:var(--muted);font-weight:500}
.float-chip.c1{top:-26px;right:-14px;animation-delay:.8s}
.float-chip.c1 .fico{background:var(--accent-soft)}
.float-chip.c2{bottom:-24px;left:-20px;animation-delay:1.6s}
.float-chip.c2 .fico{background:var(--brand-soft)}

/* ---------- 信任滚动条 ---------- */
.marquee{background:var(--brand-deep);color:rgba(255,255,255,.85);overflow:hidden;padding:15px 0;
  -webkit-mask-image:linear-gradient(90deg,transparent,#000 12%,#000 88%,transparent);
  mask-image:linear-gradient(90deg,transparent,#000 12%,#000 88%,transparent);}
.marquee-track{display:flex;gap:0;width:max-content;animation:scrollX 26s linear infinite}
.marquee:hover .marquee-track{animation-play-state:paused}
.marquee-track span{display:inline-flex;align-items:center;gap:26px;padding:0 13px;font-size:13.5px;
  letter-spacing:.12em;font-weight:600;white-space:nowrap}
.marquee-track span::after{content:"";width:5px;height:5px;border-radius:50%;background:var(--accent)}
@keyframes scrollX{to{transform:translateX(-50%)}}

/* ---------- 数据带 ---------- */
.stats{background:linear-gradient(135deg,#0C4A37,#0A3B2B 55%,#0E5540);color:#fff;padding:64px 0;position:relative;overflow:hidden}
.stats::before{content:"";position:absolute;inset:0;
  background-image:radial-gradient(rgba(255,255,255,.09) 1px,transparent 1px);background-size:26px 26px;
  -webkit-mask-image:radial-gradient(ellipse 80% 90% at 50% 50%,#000 20%,transparent 80%);
  mask-image:radial-gradient(ellipse 80% 90% at 50% 50%,#000 20%,transparent 80%);}
.stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;position:relative;text-align:center}
.stat-item{padding:10px 8px;border-radius:18px;transition:background .3s}
.stat-item:hover{background:rgba(255,255,255,.05)}
.stat-item + .stat-item{border-left:1px solid rgba(255,255,255,.12)}
.stat-num{font-size:clamp(34px,3.6vw,46px);font-weight:800;letter-spacing:.01em;font-variant-numeric:tabular-nums}
.stat-num sup{font-size:.5em;font-weight:700;top:-.6em;color:var(--accent)}
.stat-cn{font-size:14px;color:rgba(255,255,255,.92);margin-top:6px;font-weight:600}
.stat-en{font-size:10.5px;letter-spacing:.24em;text-transform:uppercase;color:rgba(255,255,255,.5);margin-top:3px}

/* ---------- 区块通用 ---------- */
.section{padding:96px 0}
.section.alt{background:var(--bg-soft)}
.sec-head{max-width:640px;margin:0 auto 56px;text-align:center}
.sec-head h2{font-size:clamp(28px,3.2vw,40px);font-weight:800;color:var(--brand-deep);letter-spacing:.01em}
.sec-head .sub{color:var(--muted);margin-top:14px;font-size:16px}
.sec-head .eyebrow{margin-bottom:14px}

/* ---------- 优势卡片 ---------- */
.grid-4{display:grid;grid-template-columns:repeat(4,1fr);gap:22px}
.feat{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:30px 26px;
  transition:transform .3s ease,box-shadow .3s ease,border-color .3s ease;position:relative;overflow:hidden;
}
.feat::before{content:"";position:absolute;top:0;left:0;right:0;height:3px;border-radius:3px 3px 0 0;
  background:linear-gradient(90deg,var(--brand),#19B98C);transform:scaleX(0);transform-origin:left;
  transition:transform .35s ease}
.feat:hover{transform:translateY(-6px);box-shadow:var(--shadow-sm);border-color:#DCE8E1}
.feat:hover::before{transform:scaleX(1)}
.feat .ico{
  width:54px;height:54px;border-radius:16px;background:var(--brand-soft);color:var(--brand);
  display:grid;place-items:center;margin-bottom:18px;transition:.3s;
}
.feat .ico svg{width:26px;height:26px}
.feat:hover .ico{background:var(--brand);color:#fff;transform:rotate(-6deg)}
.feat h3{font-size:17.5px;margin-bottom:9px;color:var(--ink)}
.feat p{color:var(--muted);font-size:14px;line-height:1.75}

/* ---------- 师资卡片 ---------- */
.teacher{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:24px;
  display:flex;flex-direction:column;gap:12px;position:relative;
  transition:transform .3s ease,box-shadow .3s ease;
}
.teacher:hover{transform:translateY(-6px);box-shadow:var(--shadow-lg)}
.teacher .rank{
  position:absolute;top:16px;right:16px;font-size:11px;font-weight:700;letter-spacing:.08em;
  color:var(--accent);background:var(--accent-soft);padding:3px 10px;border-radius:999px;
}
.teacher .top{display:flex;align-items:center;gap:13px}
.avatar{width:56px;height:56px;border-radius:50%;color:#fff;display:grid;place-items:center;
  font-weight:800;font-size:21px;background:linear-gradient(135deg,var(--brand),#0AA078);
  box-shadow:0 6px 14px rgba(14,124,95,.28);flex-shrink:0}
.teacher .name{font-weight:700;font-size:16.5px;display:flex;align-items:center;gap:6px}
.teacher .name .v{color:var(--brand);display:inline-flex}
.teacher .name .v svg{width:15px;height:15px}
.teacher .meta{font-size:13px;color:var(--muted);margin-top:2px}
.teacher .subjects{display:flex;flex-wrap:wrap;gap:6px}
.chip{background:var(--brand-soft);color:var(--brand);font-size:12px;font-weight:600;padding:3px 11px;border-radius:999px}
.teacher .bio{font-size:13.5px;color:var(--ink-2);line-height:1.7;flex:1}
.teacher .foot{display:flex;justify-content:space-between;align-items:center;padding-top:14px;border-top:1px dashed var(--line)}
.teacher .price{color:var(--accent);font-weight:800;font-size:19px}
.teacher .price small{color:var(--muted);font-weight:500;font-size:12px}

/* ---------- 流程 ---------- */
.steps{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;counter-reset:s;position:relative}
.steps::before{content:"";position:absolute;top:27px;left:6%;right:6%;height:2px;
  background:repeating-linear-gradient(90deg,var(--brand) 0 10px,transparent 10px 20px);opacity:.35}
.step{background:var(--card);border:1px solid var(--line);border-radius:20px;padding:26px 22px;position:relative;text-align:left}
.step::before{
  counter-increment:s;content:counter(s,decimal-leading-zero);
  position:absolute;top:-16px;left:22px;min-width:46px;height:34px;padding:0 10px;border-radius:999px;
  background:var(--brand-deep);color:#fff;display:grid;place-items:center;font-weight:800;font-size:13px;
  letter-spacing:.06em;box-shadow:0 8px 18px rgba(10,59,43,.28);
}
.step h4{margin:16px 0 8px;font-size:16.5px;color:var(--ink)}
.step p{color:var(--muted);font-size:13.5px;line-height:1.75}
.step .s-ico{position:absolute;top:18px;right:18px;font-size:22px;opacity:.9}

/* ---------- 科目 ---------- */
.subjects{display:flex;flex-wrap:wrap;gap:12px;justify-content:center;max-width:900px;margin:0 auto}
.subjects .s{
  background:var(--card);border:1px solid var(--line);border-radius:14px;padding:13px 22px;font-weight:600;font-size:14.5px;
  display:inline-flex;align-items:center;gap:8px;transition:.25s;cursor:default;
}
.subjects .s:hover{background:var(--brand);color:#fff;border-color:var(--brand);
  transform:translateY(-3px);box-shadow:0 10px 22px rgba(14,124,95,.25)}

/* ---------- 家长评价 ---------- */
.voices-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}
.voice{
  background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:28px 26px;
  display:flex;flex-direction:column;gap:14px;transition:transform .3s,box-shadow .3s;
}
.voice:hover{transform:translateY(-5px);box-shadow:var(--shadow-sm)}
.voice .quote-mark{font-size:44px;line-height:1;color:var(--brand);font-family:Georgia,serif;height:22px}
.voice p{font-size:14.5px;color:var(--ink-2);line-height:1.85;flex:1}
.voice .who{display:flex;align-items:center;gap:12px;padding-top:14px;border-top:1px dashed var(--line)}
.voice .who .av{width:42px;height:42px;border-radius:50%;display:grid;place-items:center;color:#fff;font-weight:700;font-size:15px}
.voice .who b{font-size:14px;display:block}
.voice .who span{font-size:12px;color:var(--muted)}

/* ---------- FAQ ---------- */
.faq{max-width:760px;margin:0 auto;display:flex;flex-direction:column;gap:14px}
.faq details{background:var(--card);border:1px solid var(--line);border-radius:18px;padding:0 24px;transition:.25s}
.faq details[open]{border-color:#CFE4DA;box-shadow:var(--shadow-sm)}
.faq summary{
  list-style:none;cursor:pointer;display:flex;align-items:center;justify-content:space-between;gap:16px;
  padding:20px 0;font-weight:700;font-size:15.5px;color:var(--ink);
}
.faq summary::-webkit-details-marker{display:none}
.faq summary .fx{
  width:30px;height:30px;border-radius:50%;background:var(--brand-soft);color:var(--brand);
  display:grid;place-items:center;flex-shrink:0;transition:.3s;font-size:18px;font-weight:600;
}
.faq details[open] summary .fx{background:var(--brand);color:#fff;transform:rotate(45deg)}
.faq .ans{padding:0 0 20px;color:var(--muted);font-size:14px;line-height:1.85}

/* ---------- CTA 横幅 + 客服二维码 ---------- */
.cta-band{
  position:relative;overflow:hidden;
  background:linear-gradient(120deg,#0C4A37,#0E7C5F 60%,#19A37B);
  color:#fff;border-radius:32px;padding:70px 40px;text-align:center;
  box-shadow:var(--shadow-lg);
}
.cta-band::before{content:"";position:absolute;inset:0;
  background-image:radial-gradient(rgba(255,255,255,.12) 1px,transparent 1px);background-size:24px 24px;
  -webkit-mask-image:radial-gradient(ellipse 70% 80% at 50% 50%,#000 20%,transparent 80%);
  mask-image:radial-gradient(ellipse 70% 80% at 50% 50%,#000 20%,transparent 80%);}
.cta-band .eyebrow{color:#FFD9A8;justify-content:center}
.cta-band .eyebrow-line{background:#FFD9A8}
.cta-band h2{color:#fff;font-size:clamp(26px,3vw,38px);font-weight:800;position:relative}
.cta-band p{opacity:.88;margin:16px auto 32px;max-width:520px;font-size:16px;position:relative}
.cta-band .btn{position:relative}
/* 已上传二维码：左右双栏（左文案 / 右二维码卡片） */
.cta-band:not(.solo){display:flex;align-items:center;gap:48px;text-align:left;padding:56px 52px}
.cta-band:not(.solo) .cta-main{flex:1;min-width:0}
.cta-band:not(.solo) .eyebrow{justify-content:flex-start}
.cta-band:not(.solo) p{margin:16px 0 32px}
.cta-qr{flex:none;width:212px;background:#fff;color:var(--text);border-radius:20px;padding:16px;text-align:center;position:relative;box-shadow:0 18px 40px rgba(0,0,0,.28)}
.cta-qr img{width:100%;aspect-ratio:1/1;object-fit:cover;border-radius:12px;display:block}
.cta-qr-t{font-weight:800;margin-top:12px;font-size:15px}
.cta-qr-d{font-size:12px;color:var(--muted);margin-top:6px;line-height:1.6}
@media(max-width:860px){
  .cta-band:not(.solo){flex-direction:column;text-align:center;gap:28px;padding:48px 24px}
  .cta-band:not(.solo) .eyebrow{justify-content:center}
  .cta-band:not(.solo) p{margin:16px auto 32px}
}

/* ---------- 页脚 ---------- */
.footer{background:#10201A;color:#A9B8B0;padding:70px 0 0;margin-top:96px}
.footer-grid{display:grid;grid-template-columns:1.5fr 1fr 1fr 1.2fr;gap:40px;padding-bottom:48px}
.footer h4{color:#fff;margin-bottom:18px;font-size:15px;letter-spacing:.06em}
.footer .f-brand{display:flex;align-items:center;gap:11px;font-weight:800;font-size:20px;color:#fff;margin-bottom:16px}
.footer .f-brand .logo-mark{box-shadow:none}
.footer .f-desc{font-size:13.5px;line-height:1.9;max-width:300px}
.footer a{display:block;margin-bottom:11px;font-size:13.5px;transition:.2s}
.footer a:hover{color:#3EDCA6;transform:translateX(3px)}
.footer .social{display:flex;gap:10px;margin-top:18px}
.footer .social a{
  width:36px;height:36px;border-radius:10px;background:rgba(255,255,255,.07);display:grid;place-items:center;
  margin:0;transition:.25s;
}
.footer .social a:hover{background:var(--brand);transform:translateY(-3px)}
.footer .social svg{width:17px;height:17px}
.footer .copy{border-top:1px solid rgba(255,255,255,.08);padding:22px 0;font-size:12.5px;color:#6E7E76;
  display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap}

/* ---------- 滚动渐显（仅 JS 生效时隐藏，JS 失效时内容直接可见） ---------- */
.js .reveal{opacity:0;transform:translateY(28px);transition:opacity .8s cubic-bezier(.2,.6,.2,1),transform .8s cubic-bezier(.2,.6,.2,1)}
.js .reveal.in{opacity:1;transform:none}
@media(prefers-reduced-motion:reduce){
  .js .reveal{opacity:1;transform:none;transition:none}
  .marquee-track{animation:none}
  .lesson-card,.float-chip{animation:none}
}

/* ---------- 响应式 ---------- */
@media(max-width:960px){
  .hero{padding-top:130px}
  .hero-grid{grid-template-columns:1fr;gap:44px}
  .hero-visual{max-width:460px;margin:0 auto}
  .float-chip.c1{right:0}
  .float-chip.c2{left:0}
  .grid-4,.steps,.voices-grid{grid-template-columns:repeat(2,1fr)}
  .steps::before{display:none}
  .stats-grid{grid-template-columns:repeat(2,1fr);gap:36px 24px}
  .stat-item + .stat-item{border-left:none}
  .nav-links{
    position:absolute;top:76px;left:4vw;right:4vw;background:#fff;border-radius:18px;box-shadow:var(--shadow-lg);
    flex-direction:column;gap:0;padding:10px 0;display:none;border:1px solid var(--line);
  }
  .site-head.open .nav-links{display:flex}
  .nav-links a{padding:13px 22px;font-size:15px}
  .nav-links a::after{display:none}
  .burger{display:flex}
  /* 移动端头部登录入口默认展示「家长登录」：隐藏老师入驻，家长登录提升为主按钮样式 */
  .head-cta .btn-primary{display:none}
  .head-cta .btn-ghost{
    background:var(--brand);color:#fff;border-color:var(--brand);
    box-shadow:0 10px 26px rgba(14,124,95,.32);
  }
  .head-cta .btn-ghost:hover{background:#0B6C52;border-color:#0B6C52;color:#fff}
}
@media(max-width:600px){
  .grid-4,.steps,.voices-grid{grid-template-columns:1fr}
  .footer-grid{grid-template-columns:1fr 1fr}
  .hero .cta .btn{width:100%}
  .section{padding:70px 0}
}

/* ---------- AI 答疑悬浮入口（后台「系统信息」开关控制） ---------- */
.ai-fab{
  position:fixed;right:26px;bottom:26px;z-index:80;
  display:inline-flex;align-items:center;gap:9px;
  padding:13px 22px;border-radius:999px;
  background:linear-gradient(135deg,var(--brand-deep),var(--brand));
  color:#fff;font-weight:700;font-size:14.5px;
  box-shadow:0 14px 34px rgba(10,59,43,.35);
  transition:transform .25s ease,box-shadow .25s ease;
}
.ai-fab svg{width:18px;height:18px;flex-shrink:0}
.ai-fab:hover{transform:translateY(-3px);box-shadow:0 18px 42px rgba(10,59,43,.45)}
.ai-fab::before{
  content:"";position:absolute;inset:0;border-radius:inherit;pointer-events:none;
  animation:aiPulse 2.8s infinite;
}
@keyframes aiPulse{
  0%{box-shadow:0 0 0 0 rgba(255,122,89,.5)}
  70%{box-shadow:0 0 0 16px rgba(255,122,89,0)}
  100%{box-shadow:0 0 0 0 rgba(255,122,89,0)}
}
@media(max-width:600px){
  .ai-fab{right:14px;bottom:14px;padding:11px 18px;font-size:13.5px}
}
@media(prefers-reduced-motion:reduce){
  .ai-fab::before{animation:none}
}