:root{
  --brand:#2D7CF6; --brand-d:#1E5FD8; --brand-2:#7C5CFC; --cyan:#16C2C2;
  --ink:#0F172A; --sub:#475569; --muted:#94A3B8;
  --bg:#F6F8FC; --card:#FFFFFF; --line:#E6EBF3; --line-2:#EEF2F8;
  --ok:#16A34A; --warn:#EAB308; --danger:#E23A3A;
  --radius:16px; --radius-sm:10px; --shadow:0 10px 30px rgba(15,23,42,.07);
  --shadow-sm:0 4px 14px rgba(15,23,42,.06);
  --max:1200px;
}
*{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;}
body{font-family:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Microsoft YaHei",sans-serif;background:var(--bg);color:var(--ink);line-height:1.6;-webkit-font-smoothing:antialiased;}
a{text-decoration:none;color:inherit;}
img{max-width:100%;display:block;}
.container{max-width:var(--max);margin:0 auto;padding:0 20px;}
.muted{color:var(--muted);}
.sub{color:var(--sub);}

/* 顶部导航 */
header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.86);backdrop-filter:blur(14px);border-bottom:1px solid var(--line);}
.nav{max-width:var(--max);margin:0 auto;padding:0 20px;height:66px;display:flex;align-items:center;justify-content:space-between;gap:16px;}
.brand{display:flex;align-items:center;gap:12px;}
.brand .logo{height:38px;}
.brand .name{font-size:20px;font-weight:800;letter-spacing:.5px;}
.nav-links{display:flex;align-items:center;gap:6px;}
.nav-links a{padding:9px 14px;border-radius:10px;color:var(--sub);font-weight:500;transition:.2s;}
.nav-links a:hover,.nav-links a.active{color:var(--brand);background:#EFF4FF;}
.nav-right{display:flex;align-items:center;gap:12px;}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:none;cursor:pointer;font-weight:600;font-size:15px;border-radius:12px;padding:11px 20px;transition:.22s;font-family:inherit;}
.btn-primary{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff;box-shadow:0 8px 20px rgba(45,124,246,.28);}
.btn-primary:hover{filter:brightness(1.05);transform:translateY(-2px);}
.btn-ghost{background:#EFF4FF;color:var(--brand);}
.btn-ghost:hover{background:#E2ECFF;}
.btn-outline{border:1.5px solid var(--brand);color:var(--brand);background:transparent;}
.btn-outline:hover{background:var(--brand);color:#fff;}
.btn-sm{padding:7px 14px;font-size:13.5px;border-radius:10px;}
.btn-block{width:100%;}
.pill{background:#EAF1FF;color:var(--brand);padding:5px 12px;border-radius:999px;font-size:13px;font-weight:600;}
.menu-btn{display:none;flex-direction:column;gap:5px;background:none;border:none;cursor:pointer;padding:8px;}
.menu-btn span{width:22px;height:2px;background:var(--ink);border-radius:2px;}

/* 通用区块 */
section{padding:72px 0;}
.sec-head{text-align:center;max-width:720px;margin:0 auto 44px;}
.sec-head h2{font-size:clamp(26px,3.4vw,38px);font-weight:800;letter-spacing:-.5px;}
.sec-head p{color:var(--sub);margin-top:12px;font-size:16px;}
.divider{width:54px;height:5px;border-radius:3px;background:linear-gradient(90deg,var(--brand),var(--brand-2));margin:0 auto 18px;}

/* Hero */
.hero{position:relative;overflow:hidden;background:radial-gradient(1200px 500px at 80% -10%,rgba(124,92,252,.18),transparent),linear-gradient(180deg,#EEF4FF,#F6F8FC);}
.hero .container{display:grid;grid-template-columns:1.05fr .95fr;gap:48px;align-items:center;padding:78px 20px;}
.hero h1{font-size:clamp(30px,4.6vw,52px);line-height:1.12;font-weight:850;letter-spacing:-1px;}
.hero h1 .grad{background:linear-gradient(120deg,var(--brand),var(--brand-2));-webkit-background-clip:text;background-clip:text;color:transparent;}
.hero p.lead{color:var(--sub);font-size:18px;margin:20px 0 30px;max-width:520px;}
.hero-cta{display:flex;gap:14px;flex-wrap:wrap;}
.hero-stats{display:flex;gap:30px;margin-top:38px;}
.hero-stats .num{font-size:26px;font-weight:800;color:var(--ink);}
.hero-stats .lbl{font-size:13px;color:var(--muted);}
.hero-card{position:relative;background:#fff;border:1px solid var(--line);border-radius:24px;padding:26px;box-shadow:var(--shadow);}
.hero-card .sticker{position:absolute;top:-26px;right:-14px;width:120px;}
.hero-card h3{font-size:19px;margin-bottom:14px;}
.hero-card ul{list-style:none;display:grid;gap:12px;}
.hero-card li{display:flex;gap:10px;align-items:flex-start;color:var(--sub);font-size:15px;}
.hero-card li .dot{flex:none;width:20px;height:20px;border-radius:6px;background:#EAF1FF;color:var(--brand);display:grid;place-items:center;font-size:12px;font-weight:800;margin-top:2px;}

/* 能力卡片 */
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:22px;}
.grid-4{display:grid;grid-template-columns:repeat(4,1fr);gap:20px;}
.feature{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:26px;transition:.25s;}
.feature:hover{transform:translateY(-5px);box-shadow:var(--shadow);border-color:#D6E2FF;}
.feature .ic{width:50px;height:50px;border-radius:14px;display:grid;place-items:center;background:linear-gradient(135deg,#EAF1FF,#F1ECFF);color:var(--brand);margin-bottom:16px;}
.feature h3{font-size:18px;margin-bottom:8px;}
.feature p{color:var(--sub);font-size:14.5px;}

/* 课程网格 */
.course-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:24px;}
.course-card{position:relative;background:var(--card);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;display:flex;flex-direction:column;transition:.25s;}
.course-card:hover{transform:translateY(-6px);box-shadow:var(--shadow);border-color:#D6E2FF;}
.course-card .cover{aspect-ratio:16/9;object-fit:cover;width:100%;background:#EEF2F8;}
.course-card .body{padding:18px;display:flex;flex-direction:column;flex:1;}
.course-card .tags{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:10px;}
.tag{font-size:12px;background:#EFF4FF;color:var(--brand);padding:3px 10px;border-radius:7px;font-weight:600;}
.course-card h3{font-size:17px;line-height:1.4;margin-bottom:8px;}
.course-card .desc{color:var(--sub);font-size:13.5px;flex:1;margin-bottom:14px;}
.course-card .foot{display:flex;align-items:center;justify-content:space-between;gap:10px;}
.price{color:var(--brand);font-weight:800;font-size:19px;}
.price small{font-size:12px;color:var(--muted);font-weight:600;}
.ribbon{position:absolute;top:12px;left:12px;background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff;font-size:12px;font-weight:700;padding:4px 10px;border-radius:8px;z-index:2;}

/* 筛选条 */
.toolbar{display:flex;gap:12px;flex-wrap:wrap;align-items:center;margin-bottom:28px;}
.toolbar .search{flex:1;min-width:220px;position:relative;}
.toolbar .search input{width:100%;padding:11px 14px 11px 38px;border:1px solid var(--line);border-radius:12px;font-size:15px;background:#fff;font-family:inherit;}
.toolbar .search svg{position:absolute;left:12px;top:50%;transform:translateY(-50%);color:var(--muted);}
.chips{display:flex;gap:8px;flex-wrap:wrap;}
.chip{border:1px solid var(--line);background:#fff;color:var(--sub);padding:8px 15px;border-radius:999px;font-size:14px;cursor:pointer;font-family:inherit;transition:.2s;}
.chip:hover{border-color:var(--brand);color:var(--brand);}
.chip.active{background:var(--brand);border-color:var(--brand);color:#fff;}

/* 详情 */
.detail-wrap{display:grid;grid-template-columns:1.4fr 1fr;gap:40px;align-items:start;}
.detail-cover{border-radius:var(--radius);overflow:hidden;border:1px solid var(--line);}
.detail-cover img{width:100%;aspect-ratio:16/9;object-fit:cover;}
.detail-main h1{font-size:30px;font-weight:850;margin:6px 0 14px;}
.detail-box{position:sticky;top:90px;background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:24px;box-shadow:var(--shadow-sm);}
.detail-box .price{font-size:30px;}
.lesson-list{list-style:none;display:grid;gap:10px;margin-top:16px;}
.lesson-list li{display:flex;gap:10px;align-items:center;color:var(--sub);}
.lesson-list .n{width:24px;height:24px;border-radius:50%;background:#EAF1FF;color:var(--brand);display:grid;place-items:center;font-size:12px;font-weight:700;flex:none;}
.prose{color:var(--sub);font-size:15.5px;}
.prose p{margin:10px 0;}
.prose ul{margin:10px 0 10px 20px;}
.prose li{margin:6px 0;}

/* 表单 / 弹窗 */
.modal-mask{position:fixed;inset:0;background:rgba(15,23,42,.5);backdrop-filter:blur(4px);display:none;align-items:center;justify-content:center;padding:18px;z-index:100;}
.modal-mask.show{display:flex;}
.modal{width:100%;max-width:460px;background:#fff;border-radius:18px;padding:28px;position:relative;box-shadow:var(--shadow);max-height:90vh;overflow:auto;}
.modal h3{font-size:21px;margin-bottom:6px;}
.modal .sub{margin-bottom:20px;font-size:14px;}
.modal-close{position:absolute;top:16px;right:16px;border:none;background:#F1F5F9;width:34px;height:34px;border-radius:10px;cursor:pointer;font-size:18px;color:var(--sub);}
.modal-close:hover{background:#E2E8F0;}
.field{margin-bottom:16px;}
.field label{display:block;font-weight:600;font-size:14px;margin-bottom:7px;}
.field input,.field textarea,.field select{width:100%;padding:11px 13px;border:1px solid var(--line);border-radius:11px;font-size:15px;font-family:inherit;background:#fff;}
.field input:focus,.field textarea:focus,.field select:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 3px rgba(45,124,246,.15);}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:14px;}
.tabs{display:flex;gap:8px;background:#EEF2F8;padding:5px;border-radius:12px;margin-bottom:22px;}
.tab{flex:1;text-align:center;padding:9px;border-radius:9px;cursor:pointer;font-weight:600;color:var(--sub);font-size:14.5px;}
.tab.active{background:#fff;color:var(--brand);box-shadow:var(--shadow-sm);}

/* 我的 */
.dash{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:18px;margin-bottom:36px;}
.stat{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow-sm);}
.stat .v{font-size:30px;font-weight:850;color:var(--brand);}
.stat .k{color:var(--sub);font-size:14px;margin-top:4px;}

/* 管理员 */
.admin-shell{display:grid;grid-template-columns:230px 1fr;min-height:100vh;}
.admin-side{background:#0F172A;color:#CBD5E1;padding:22px 16px;}
.admin-side .a-brand{display:flex;align-items:center;gap:10px;padding:6px 8px 18px;color:#fff;font-weight:800;font-size:17px;}
.admin-side .a-brand .logo{height:30px;}
.admin-side a{display:flex;align-items:center;gap:10px;padding:11px 12px;border-radius:10px;color:#CBD5E1;font-size:14.5px;cursor:pointer;transition:.2s;}
.admin-side a:hover{background:rgba(255,255,255,.08);color:#fff;}
.admin-side a.active{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff;}
.admin-main{padding:28px 32px;overflow:auto;}
.admin-main h2{font-size:24px;font-weight:800;margin-bottom:20px;}
.table{width:100%;border-collapse:collapse;background:#fff;border:1px solid var(--line);border-radius:14px;overflow:hidden;}
.table th,.table td{padding:13px 14px;text-align:left;font-size:14px;border-bottom:1px solid var(--line-2);}
.table th{background:#F8FAFC;color:var(--sub);font-weight:700;font-size:13px;}
.table tr:last-child td{border-bottom:none;}
.table tr:hover td{background:#FAFCFF;}
.badge-ok{background:#E7F8EE;color:var(--ok);padding:3px 10px;border-radius:7px;font-size:12px;font-weight:700;}
.badge-add{background:#EFF4FF;color:var(--brand);padding:3px 10px;border-radius:7px;font-size:12px;font-weight:700;}
.badge-off{background:#F1F5F9;color:var(--muted);padding:3px 10px;border-radius:7px;font-size:12px;font-weight:700;}
.badge-ban{background:#FDECEC;color:var(--danger);padding:3px 10px;border-radius:7px;font-size:12px;font-weight:700;}
.tag-input{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:10px;font-size:14px;font-family:inherit;}
.toast{position:fixed;left:50%;bottom:34px;transform:translateX(-50%) translateY(20px);background:#0F172A;color:#fff;padding:13px 22px;border-radius:12px;font-size:14.5px;opacity:0;pointer-events:none;transition:.25s;z-index:200;box-shadow:var(--shadow);}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0);}
.empty{text-align:center;color:var(--muted);padding:50px 0;}

footer.foot{border-top:1px solid var(--line);background:#fff;padding:40px 0;color:var(--sub);font-size:14px;}
.foot .container{display:flex;justify-content:space-between;flex-wrap:wrap;gap:16px;}

@media(max-width:980px){
  .hero .container{grid-template-columns:1fr;padding:54px 20px;}
  .detail-wrap{grid-template-columns:1fr;}
  .detail-box{position:static;}
  .grid-3,.grid-4{grid-template-columns:repeat(2,1fr);}
  .admin-shell{grid-template-columns:1fr;}
  .admin-side{display:flex;overflow:auto;}
  .admin-side .a-brand{display:none;}
  .admin-side a{flex:none;}
}
@media(max-width:640px){
  .grid-3,.grid-4{grid-template-columns:1fr;}
  .nav-links{display:none;}
  .menu-btn{display:flex;}
  .mobile-nav{display:none;flex-direction:column;gap:4px;padding:10px 20px 16px;border-bottom:1px solid var(--line);background:#fff;}
  .mobile-nav.show{display:flex;}
  .mobile-nav a{padding:10px 0;color:var(--sub);}
  .row2{grid-template-columns:1fr;}
  .hero-stats{gap:20px;}
}