:root{
  --brand:#4f46e5; --brand2:#2563eb; --ink:#0f172a; --body:#334155; --muted:#64748b;
  --line:#e2e8f0; --bg:#f8fafc; --card:#ffffff; --ok:#16a34a; --warn:#f59e0b; --bad:#e11d48;
  --grad:linear-gradient(135deg,#4f46e5 0%,#2563eb 55%,#0ea5e9 100%);
  --radius:16px; --shadow:0 10px 30px rgba(15,23,42,.08); --shadow-lg:0 24px 60px rgba(30,41,90,.22);
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",Roboto,Helvetica,Arial,sans-serif;
  color:var(--body);background:var(--bg);line-height:1.65;-webkit-font-smoothing:antialiased}
a{color:var(--brand);text-decoration:none}
img{max-width:100%}
.wrap{max-width:1120px;margin:0 auto;padding:0 20px}
.btn{display:inline-flex;align-items:center;gap:8px;border:0;border-radius:999px;padding:12px 24px;font-size:15px;font-weight:700;
  cursor:pointer;background:var(--brand);color:#fff;transition:.16s;box-shadow:0 6px 18px rgba(79,70,229,.3)}
.btn:hover{transform:translateY(-2px);box-shadow:0 12px 26px rgba(79,70,229,.4)}
.btn.ghost{background:#fff;color:var(--brand);box-shadow:none;border:1.5px solid var(--line)}
.btn.ghost:hover{border-color:var(--brand);box-shadow:0 6px 16px rgba(79,70,229,.14)}
.btn.lg{padding:15px 34px;font-size:17px}
.btn.block{width:100%;justify-content:center}
.btn.sm{padding:8px 16px;font-size:13px}
.btn:disabled{opacity:.55;cursor:not-allowed;transform:none}

/* 顶栏 */
.nav{position:sticky;top:0;z-index:40;background:rgba(255,255,255,.86);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.nav .wrap{display:flex;align-items:center;gap:16px;height:64px}
.logo{font-weight:900;font-size:20px;color:var(--ink);display:flex;align-items:center;gap:8px}
.logo .dot{width:30px;height:30px;border-radius:9px;background:var(--grad);display:inline-flex;align-items:center;justify-content:center;color:#fff;font-size:17px}
.nav .sp{flex:1}
.nav a.link{color:var(--body);font-weight:600;font-size:14px;padding:6px 10px;border-radius:8px}
.nav a.link:hover{background:#f1f5f9;color:var(--brand)}

/* Hero */
.hero{position:relative;overflow:hidden;background:var(--grad);color:#fff;padding:66px 0 88px}
.hero::after{content:"";position:absolute;inset:0;background:
  radial-gradient(600px 300px at 85% -10%,rgba(255,255,255,.22),transparent 60%),
  radial-gradient(500px 300px at 0% 120%,rgba(255,255,255,.14),transparent 60%);pointer-events:none}
.hero .wrap{position:relative;z-index:2}
.hero .eyebrow{display:inline-block;background:rgba(255,255,255,.18);border:1px solid rgba(255,255,255,.3);
  padding:6px 14px;border-radius:999px;font-size:13px;font-weight:700;margin-bottom:18px}
.hero h1{font-size:clamp(30px,5vw,50px);line-height:1.15;margin:0 0 16px;color:#fff;font-weight:900;letter-spacing:-.5px}
.hero h1 .hl{background:linear-gradient(120deg,#fde68a,#fca5a5);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero p.lead{font-size:clamp(16px,2.2vw,20px);color:rgba(255,255,255,.92);max-width:640px;margin:0 0 28px}
.hero .cta{display:flex;gap:14px;flex-wrap:wrap;align-items:center}
.hero .btn{background:#fff;color:var(--brand)}
.hero .btn:hover{box-shadow:0 14px 30px rgba(0,0,0,.25)}
.hero .btn.ghost{background:rgba(255,255,255,.12);color:#fff;border:1.5px solid rgba(255,255,255,.5)}
.hero .philo{margin-top:26px;font-size:14px;color:rgba(255,255,255,.85)}
.hero .philo b{color:#fff}

/* 统计条 */
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin:-46px auto 0;position:relative;z-index:5}
.stat{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);padding:20px 18px;text-align:center}
.stat .n{font-size:30px;font-weight:900;color:var(--brand);line-height:1}
.stat .l{font-size:13px;color:var(--muted);margin-top:6px}

/* 区块 */
section.blk{padding:64px 0}
.blk h2{font-size:clamp(24px,3.4vw,34px);text-align:center;margin:0 0 8px;color:var(--ink);font-weight:900}
.blk .sub{text-align:center;color:var(--muted);max-width:640px;margin:0 auto 40px;font-size:16px}

/* 特性卡 */
.feat{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}
.fcard{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:26px 22px;transition:.18s}
.fcard:hover{transform:translateY(-4px);box-shadow:var(--shadow);border-color:transparent}
.fcard .ic{width:52px;height:52px;border-radius:14px;display:flex;align-items:center;justify-content:center;font-size:26px;margin-bottom:14px;background:#eef2ff}
.fcard h3{margin:0 0 8px;font-size:19px;color:var(--ink)}
.fcard p{margin:0;color:var(--body);font-size:15px}
.fcard .tag{display:inline-block;margin-top:12px;font-size:12px;font-weight:700;color:var(--brand);background:#eef2ff;padding:3px 10px;border-radius:999px}

/* 学段两卡 */
.stages{display:grid;grid-template-columns:1fr 1fr;gap:22px}
.scard{border-radius:var(--radius);padding:30px;color:#fff;position:relative;overflow:hidden}
.scard.cz{background:linear-gradient(135deg,#4f46e5,#7c3aed)}
.scard.hs{background:linear-gradient(135deg,#0ea5e9,#2563eb)}
.scard h3{font-size:24px;margin:0 0 6px;color:#fff}
.scard .big{font-size:15px;opacity:.92;margin-bottom:16px}
.scard ul{margin:0;padding-left:18px;font-size:14px;opacity:.95}
.scard ul li{margin:4px 0}
.scard .chips{margin-top:14px;display:flex;flex-wrap:wrap;gap:6px}
.scard .chip{background:rgba(255,255,255,.2);border-radius:999px;padding:4px 11px;font-size:12px;font-weight:600}

/* 分享 */
.share{background:linear-gradient(135deg,#0f172a,#1e293b);border-radius:20px;padding:40px;color:#fff;text-align:center}
.share h2{color:#fff}
.share .sub{color:rgba(255,255,255,.7)}
.share .row{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-top:8px}

/* 页脚 */
footer{padding:40px 0;border-top:1px solid var(--line);color:var(--muted);font-size:14px;text-align:center}

/* 模态 */
.ov{position:fixed;inset:0;background:rgba(15,23,42,.55);z-index:100;display:none;align-items:center;justify-content:center;padding:16px;overflow:auto}
.ov.on{display:flex}
.modal{background:#fff;border-radius:20px;max-width:420px;width:100%;box-shadow:var(--shadow-lg);padding:30px 28px;position:relative}
.modal h2{margin:0 0 4px;font-size:23px;color:var(--ink)}
.modal .msub{color:var(--muted);font-size:14px;margin-bottom:18px}
.modal .x{position:absolute;top:16px;right:18px;cursor:pointer;color:var(--muted);font-size:20px;border:0;background:none}
.field{margin-bottom:14px}
.field label{display:block;font-size:13px;font-weight:700;color:var(--body);margin-bottom:6px}
.field input,.field select{width:100%;padding:11px 13px;border:1.5px solid var(--line);border-radius:11px;font-size:15px;font-family:inherit;background:#fff}
.field input:focus,.field select:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px rgba(79,70,229,.14)}
.field .hint{font-size:12px;color:var(--muted);margin-top:4px}
.tabs{display:flex;gap:6px;background:#f1f5f9;border-radius:12px;padding:4px;margin-bottom:20px}
.tabs button{flex:1;border:0;background:none;padding:9px;border-radius:9px;font-weight:700;font-size:14px;color:var(--muted);cursor:pointer}
.tabs button.on{background:#fff;color:var(--brand);box-shadow:0 2px 6px rgba(0,0,0,.06)}
.msg{padding:10px 12px;border-radius:10px;font-size:13px;margin-bottom:14px;display:none}
.msg.err{display:block;background:#fef2f2;color:#b91c1c;border:1px solid #fecaca}
.msg.ok{display:block;background:#f0fdf4;color:#15803d;border:1px solid #bbf7d0}

/* 学习中心 hub */
.hub{max-width:760px;margin:40px auto;padding:0 20px}
.hub .card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:26px;box-shadow:var(--shadow);margin-bottom:18px}
.hub .enter{background:var(--grad);color:#fff;border:0}
.hub .enter h2{color:#fff;margin:0 0 6px}
.toast{position:fixed;left:50%;bottom:30px;transform:translateX(-50%);background:#0f172a;color:#fff;padding:11px 20px;border-radius:999px;font-size:14px;z-index:200;opacity:0;transition:.25s;pointer-events:none}
.toast.on{opacity:1}
.hidden{display:none!important}

@media(max-width:820px){
  .stats{grid-template-columns:repeat(2,1fr)}
  .feat{grid-template-columns:1fr}
  .stages{grid-template-columns:1fr}
  .nav a.link.hide-m{display:none}
}