:root{
    --bg:#f4f6f9;
    --card:#ffffff;
    --ink:#1a2332;
    --ink-2:#475569;
    --ink-3:#94a3b8;
    --line:#e2e8f0;
    --primary:#0c4a6e;
    --primary-soft:#e0f2fe;
    --accent:#c2410c;
    --accent-soft:#fff7ed;
    --green:#166534;
    --green-soft:#f0fdf4;
    --purple:#581c87;
    --purple-soft:#faf5ff;
    --radius:14px;
  }
  *{margin:0;padding:0;box-sizing:border-box}
  html{scroll-behavior:smooth}
  body{
    font-family:"Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;
    background:var(--bg);color:var(--ink);line-height:1.75;font-size:15px;
  }
  /* ===== 顶部导航 ===== */
  .nav{
    position:fixed;top:0;left:0;right:0;z-index:100;
    background:rgba(255,255,255,.92);backdrop-filter:blur(10px);
    border-bottom:1px solid var(--line);
  }
  .nav-inner{max-width:1200px;margin:0 auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between;height:60px}
  .nav-brand{font-weight:700;font-size:16px;color:var(--primary);letter-spacing:.5px}
  .nav-links{display:flex;gap:6px;flex-wrap:wrap}
  .nav-links a{
    text-decoration:none;color:var(--ink-2);font-size:13px;padding:6px 12px;
    border-radius:8px;transition:all .2s;
  }
  .nav-links a:hover{background:var(--primary-soft);color:var(--primary)}
  @media(max-width:768px){.nav-links{display:none}}

  /* ===== Hero ===== */
  .hero{
    margin-top:60px;padding:72px 24px 56px;
    background:linear-gradient(135deg,#0c4a6e 0%,#075985 50%,#0369a1 100%);
    color:#fff;text-align:center;position:relative;overflow:hidden;
  }
  .hero::before{
    content:"";position:absolute;inset:0;
    background:radial-gradient(circle at 20% 30%,rgba(255,255,255,.08) 0%,transparent 50%),
               radial-gradient(circle at 80% 70%,rgba(194,65,12,.15) 0%,transparent 40%);
  }
  .hero-tag{display:inline-block;background:rgba(255,255,255,.15);border:1px solid rgba(255,255,255,.25);padding:5px 16px;border-radius:20px;font-size:13px;letter-spacing:1px;margin-bottom:20px;position:relative}
  .hero h1{font-size:38px;font-weight:800;margin-bottom:16px;position:relative;letter-spacing:1px}
  .hero p{font-size:16px;opacity:.85;max-width:720px;margin:0 auto 32px;position:relative}
  .hero-stats{display:flex;justify-content:center;gap:48px;flex-wrap:wrap;position:relative}
  .hero-stat .num{font-size:32px;font-weight:800;color:#fbbf24}
  .hero-stat .label{font-size:13px;opacity:.8;margin-top:2px}

  /* ===== 容器 ===== */
  .container{max-width:1100px;margin:0 auto;padding:0 24px}

  /* ===== 板块总览 ===== */
  .overview{padding:64px 0 40px}
  .section-title{text-align:center;margin-bottom:40px}
  .section-title h2{font-size:28px;font-weight:800;color:var(--ink);margin-bottom:8px}
  .section-title p{color:var(--ink-2);font-size:15px}
  .overview-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:18px}
  @media(max-width:900px){.overview-grid{grid-template-columns:repeat(2,1fr)}}
  @media(max-width:520px){.overview-grid{grid-template-columns:1fr}}
  .ov-card{
    background:var(--card);border-radius:var(--radius);padding:24px 20px;
    border-top:4px solid var(--primary);box-shadow:0 2px 12px rgba(0,0,0,.05);
    transition:transform .2s,box-shadow .2s;
  }
  .ov-card:hover{transform:translateY(-3px);box-shadow:0 8px 24px rgba(0,0,0,.1)}
  .ov-card.c1{border-top-color:#0c4a6e}
  .ov-card.c2{border-top-color:#c2410c}
  .ov-card.c3{border-top-color:#166534}
  .ov-card.c4{border-top-color:#581c87}
  .ov-num{font-size:13px;font-weight:700;color:var(--ink-3);letter-spacing:1px}
  .ov-card h3{font-size:18px;font-weight:700;margin:8px 0 6px;color:var(--ink)}
  .ov-card .range{font-size:12px;color:var(--accent);font-weight:600;margin-bottom:10px}
  .ov-card p{font-size:13px;color:var(--ink-2);line-height:1.65}

  /* ===== 板块章节 ===== */
  .block-section{padding:48px 0 24px}
  .block-header{
    border-radius:var(--radius);padding:32px 36px;margin-bottom:32px;
    display:flex;align-items:center;gap:24px;flex-wrap:wrap;
  }
  .block-header.b1{background:linear-gradient(135deg,#0c4a6e,#0369a1);color:#fff}
  .block-header.b2{background:linear-gradient(135deg,#9a3412,#c2410c);color:#fff}
  .block-header.b3{background:linear-gradient(135deg,#14532d,#166534);color:#fff}
  .block-header.b4{background:linear-gradient(135deg,#4c1d95,#581c87);color:#fff}
  .block-badge{
    width:64px;height:64px;border-radius:16px;background:rgba(255,255,255,.18);
    display:flex;align-items:center;justify-content:center;font-size:28px;font-weight:800;flex-shrink:0;
  }
  .block-header h2{font-size:24px;font-weight:800;margin-bottom:4px}
  .block-header .sub{font-size:14px;opacity:.85}
  .block-goal{
    background:var(--card);border-left:4px solid var(--accent);border-radius:0 var(--radius) var(--radius) 0;
    padding:18px 24px;margin-bottom:32px;font-size:14px;color:var(--ink-2);
  }
  .block-goal strong{color:var(--ink)}

  /* ===== 课程卡片 ===== */
  .lesson{
    background:var(--card);border-radius:var(--radius);margin-bottom:24px;
    box-shadow:0 2px 10px rgba(0,0,0,.04);overflow:hidden;
    border:1px solid var(--line);
  }
  .lesson-head{
    padding:22px 28px;display:flex;align-items:flex-start;gap:16px;
    border-bottom:1px solid var(--line);cursor:pointer;
  }
  .lesson-num{
    flex-shrink:0;width:52px;height:52px;border-radius:12px;
    display:flex;align-items:center;justify-content:center;
    font-size:20px;font-weight:800;color:#fff;
  }
  .b1 .lesson-num{background:linear-gradient(135deg,#0c4a6e,#0369a1)}
  .b2 .lesson-num{background:linear-gradient(135deg,#9a3412,#c2410c)}
  .b3 .lesson-num{background:linear-gradient(135deg,#14532d,#166534)}
  .b4 .lesson-num{background:linear-gradient(135deg,#4c1d95,#581c87)}
  .lesson-head-text{flex:1}
  .lesson-head-text h3{font-size:19px;font-weight:700;color:var(--ink);margin-bottom:4px}
  .lesson-head-text .one-liner{font-size:13px;color:var(--ink-2)}
  .lesson-toggle{flex-shrink:0;color:var(--ink-3);font-size:20px;transition:transform .3s;margin-top:8px}
  .lesson.open .lesson-toggle{transform:rotate(45deg)}
  .lesson-body{display:none;padding:0 28px 28px}
  .lesson.open .lesson-body{display:block}

  .lesson-sub{margin-top:22px}
  .lesson-sub h4{
    font-size:14px;font-weight:700;color:var(--primary);margin-bottom:10px;
    display:flex;align-items:center;gap:8px;
  }
  .lesson-sub h4::before{content:"";width:4px;height:16px;background:var(--accent);border-radius:2px}
  .goal-list{list-style:none;display:flex;flex-direction:column;gap:8px}
  .goal-list li{font-size:14px;color:var(--ink-2);padding-left:20px;position:relative}
  .goal-list li::before{content:"▸";position:absolute;left:0;color:var(--accent);font-weight:700}

  .kp-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px}
  .kp-item{
    background:var(--bg);border-radius:10px;padding:14px 16px;border:1px solid var(--line);
  }
  .kp-item .kp-name{font-size:14px;font-weight:700;color:var(--ink);margin-bottom:4px}
  .kp-item .kp-desc{font-size:12.5px;color:var(--ink-2);line-height:1.6}

  .content-points{list-style:none;display:flex;flex-direction:column;gap:10px}
  .content-points li{
    font-size:14px;color:var(--ink-2);padding:12px 16px;background:var(--bg);
    border-radius:8px;border-left:3px solid var(--primary-soft);line-height:1.7;
  }
  .content-points li strong{color:var(--ink)}

  .practice-box{
    background:var(--accent-soft);border:1px solid #fed7aa;border-radius:10px;padding:16px 20px;
  }
  .practice-box h4{color:var(--accent)!important}
  .practice-box h4::before{background:var(--accent)!important}
  .practice-box p{font-size:13.5px;color:var(--ink-2);line-height:1.75}

  /* ===== 配套服务 ===== */
  .services{padding:56px 0 64px}
  .services-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:16px}
  .svc-card{
    background:var(--card);border-radius:var(--radius);padding:24px 20px;text-align:center;
    border:1px solid var(--line);transition:transform .2s;
  }
  .svc-card:hover{transform:translateY(-3px)}
  .svc-icon{width:48px;height:48px;border-radius:12px;background:var(--primary-soft);display:flex;align-items:center;justify-content:center;margin:0 auto 12px;font-size:22px}
  .svc-card h4{font-size:15px;font-weight:700;margin-bottom:6px;color:var(--ink)}
  .svc-card p{font-size:12.5px;color:var(--ink-2);line-height:1.6}

  /* ===== 页脚 ===== */
  footer{background:var(--ink);color:#94a3b8;padding:32px 24px;text-align:center;font-size:13px}
  footer strong{color:#e2e8f0}

  /* 展开全部按钮 */
  .expand-all{
    display:block;margin:0 auto 24px;background:var(--primary);color:#fff;
    border:none;padding:10px 28px;border-radius:8px;font-size:14px;cursor:pointer;
    font-weight:600;transition:background .2s;
  }
  .expand-all:hover{background:#075985}