:root{
  --bg:#0B0B12;
  --card:#14141F;
  --footer:#0E0E17;
  --card-border:rgba(255,255,255,0.07);
  --line:rgba(255,255,255,0.07);
  --text:#F5F5F7;
  --text-2:#A6A6BD;
  --text-3:#9999B2;
  --text-4:#808099;
  --chip:#C7C7D9;
  --purple:#8B5CF6;
  --green:#22C55E;
  --brown:#B08D57;
  --pi:#E5E7EB;
  --g-purple:rgba(139,92,246,.14);
  --g-green:rgba(34,197,94,.14);
  --g-brown:rgba(176,141,87,.14);
  --g-pi:rgba(229,231,235,.12);
  --border-soft:rgba(255,255,255,.07);
  --code:#E3B8FF;
  --pre-bg:#0D0D15;
  --nav-bg:rgba(11,11,18,.92);
  --radius:18px;
  --shadow:0 12px 24px rgba(0,0,0,.35);
}
:root[data-theme="light"]{
  --bg:#FAFAFB;
  --card:#FFFFFF;
  --footer:#F2F2F5;
  --card-border:rgba(0,0,0,.08);
  --line:rgba(0,0,0,.08);
  --text:#1A1A24;
  --text-2:#4A4A5E;
  --text-3:#66667E;
  --text-4:#8A8AA0;
  --chip:#3A3A4A;
  --border-soft:rgba(0,0,0,.08);
  --code:#7C3AED;
  --pre-bg:#F4F4F7;
  --nav-bg:rgba(255,255,255,.92);
  --pi:#111827;
  --g-pi:rgba(17,24,39,.12);
  --shadow:0 12px 24px rgba(0,0,0,.08);
}
*{margin:0;padding:0;box-sizing:border-box;}
html{scroll-behavior:smooth;}
body{
  background:var(--bg);color:var(--text);
  font-family:"Noto Sans SC","Inter",sans-serif;
  -webkit-font-smoothing:antialiased;line-height:1.6;overflow-x:hidden;
}
a{text-decoration:none;color:inherit;}
ul{list-style:none;}
.wrap{width:1200px;max-width:calc(100% - 64px);margin:0 auto;}
.section{display:flex;justify-content:center;padding:80px 0;}
.section-head{display:flex;flex-direction:column;align-items:flex-start;gap:8px;margin-bottom:40px;}
.section-head .head-title{font-size:28px;font-weight:700;color:var(--text);}
.section-head .head-sub{font-size:15px;color:var(--text-2);}

/* accent theme (brown for Claude, green for Codex, pi for Pi) */
.accent-brown{--accent:var(--brown);--g-accent:var(--g-brown);}
.accent-green{--accent:var(--green);--g-accent:var(--g-green);}
.accent-pi{--accent:var(--pi);--g-accent:var(--g-pi);}

/* ===== Navbar ===== */
.nav{position:sticky;top:0;z-index:50;background:var(--nav-bg);backdrop-filter:blur(12px);border-bottom:1px solid var(--line);}
.nav-inner{height:68px;display:flex;align-items:center;justify-content:space-between;}
.logo{display:flex;align-items:center;gap:10px;font-family:"Space Grotesk",sans-serif;font-weight:700;font-size:19px;color:var(--text);}
.logo-mark{width:28px;height:28px;border-radius:8px;background:linear-gradient(135deg,#8B5CF6,#B08D57);color:#fff;display:flex;align-items:center;justify-content:center;}
.nav-links{display:flex;align-items:center;gap:28px;font-size:15px;font-weight:500;color:var(--text-2);}
.nav-links a:hover{color:var(--text);transition:color .2s;}
.nav-cta{background:var(--purple);color:#fff;font-family:"Inter";font-weight:600;font-size:14px;padding:9px 18px;border-radius:10px;}
.nav-cta:hover{filter:brightness(1.1);}
.nav-right{display:flex;align-items:center;gap:14px;}
.theme-toggle{display:inline-flex;align-items:center;justify-content:center;width:38px;height:38px;border-radius:10px;border:1px solid var(--line);background:var(--card);color:var(--text-2);cursor:pointer;transition:color .2s,border-color .2s;}
.theme-toggle:hover{color:var(--text);border-color:var(--accent);}
.theme-toggle svg{display:none;}
.theme-toggle[data-theme-now="dark"] .icon-moon{display:block;}
.theme-toggle[data-theme-now="light"] .icon-sun{display:block;}

/* ===== Breadcrumb ===== */
.breadcrumb{padding:24px 0 0;font-size:13px;color:var(--text-3);}
.breadcrumb a{color:var(--text-2);}
.breadcrumb a:hover{color:var(--text);}
.breadcrumb span{color:var(--text-4);margin:0 8px;}

/* ===== Course Hero ===== */
.course-hero{display:flex;justify-content:center;padding:48px 0 24px;}
.hero-grid{display:grid;grid-template-columns:1.2fr .8fr;gap:56px;align-items:center;}
.hero-info{display:flex;flex-direction:column;gap:20px;}
.badge{display:inline-flex;align-items:center;padding:6px 12px;border-radius:8px;font-size:13px;font-weight:500;width:fit-content;background:var(--g-accent);color:var(--accent);}
.course-h1{font-size:42px;font-weight:700;color:var(--text);letter-spacing:-.01em;line-height:1.2;}
.course-sub{font-size:16px;color:var(--text-2);line-height:1.8;}
.hero-meta{display:flex;flex-wrap:wrap;gap:16px;padding-top:4px;}
.meta-item{display:flex;align-items:center;gap:8px;font-size:14px;color:var(--text-3);}
.meta-item .dot{width:6px;height:6px;border-radius:50%;background:var(--accent);}
.hero-cta{display:flex;gap:16px;align-items:center;margin-top:8px;}
.btn-solid{display:inline-block;background:linear-gradient(90deg,#D97757,#8B5CF6);color:#fff;font-family:"Inter";font-weight:600;font-size:16px;padding:14px 28px;border-radius:12px;}
.btn-solid:hover{filter:brightness(1.08);}
.btn-ghost{display:inline-block;border:1px solid var(--line);color:var(--text-2);font-size:16px;font-weight:500;padding:14px 28px;border-radius:12px;}
.btn-ghost:hover{background:var(--border-soft);}
.hero-card{background:var(--card);border:1px solid var(--card-border);border-radius:var(--radius);box-shadow:var(--shadow);padding:28px;display:flex;flex-direction:column;gap:18px;}
.hero-card h4{font-size:15px;color:var(--text-3);font-weight:500;}
.hero-card .level{font-family:"Space Grotesk",sans-serif;font-size:40px;font-weight:700;color:var(--accent);}
.hero-card .stat-row{display:flex;gap:24px;padding-top:8px;border-top:1px solid var(--line);}
.hero-card .stat{flex:1;}
.hero-card .stat b{font-family:"Space Grotesk";font-size:22px;color:var(--text);}
.hero-card .stat span{display:block;font-size:12px;color:var(--text-4);}

/* ===== Highlights (you'll learn) ===== */
.highlights-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:14px;}
.highlight{display:flex;gap:12px;align-items:flex-start;background:var(--card);border:1px solid var(--card-border);border-radius:12px;padding:16px 18px;}
.highlight .check{flex:none;width:22px;height:22px;border-radius:50%;background:var(--g-accent);color:var(--accent);display:flex;align-items:center;justify-content:center;font-size:13px;font-weight:700;margin-top:2px;}
.highlight b{display:block;font-size:15px;color:var(--text);font-weight:600;margin-bottom:2px;}
.highlight span{font-size:13px;color:var(--text-3);}

/* ===== Curriculum ===== */
.curriculum{display:flex;flex-direction:column;gap:14px;}
.cur-module{background:var(--card);border:1px solid var(--card-border);border-radius:16px;overflow:hidden;}
.cur-module[open]{border-color:var(--accent);}
.cur-head{list-style:none;cursor:pointer;padding:20px 24px;display:flex;align-items:center;gap:16px;}
.cur-head::-webkit-details-marker{display:none;}
.cur-index{flex:none;font-family:"Space Grotesk";font-size:16px;font-weight:700;color:var(--accent);}
.cur-title{flex:1;font-size:16px;font-weight:600;color:var(--text);}
.cur-meta{flex:none;font-size:12px;color:var(--text-3);display:flex;align-items:center;gap:12px;}
.cur-meta .n{color:var(--text-2);}
.cur-arrow{flex:none;width:24px;height:24px;border-radius:7px;background:var(--g-accent);color:var(--accent);display:flex;align-items:center;justify-content:center;font-size:15px;transition:transform .2s;}
.cur-module[open] .cur-arrow{transform:rotate(90deg);}
.cur-lessons{padding:0 24px 8px;display:flex;flex-direction:column;}
.cur-lesson{display:flex;align-items:center;gap:12px;padding:12px 0;border-top:1px solid var(--line);font-size:14px;color:var(--text-2);}
.cur-lesson .play{flex:none;width:20px;height:20px;border-radius:6px;border:1px solid var(--line);color:var(--text-3);display:flex;align-items:center;justify-content:center;font-size:10px;}
.cur-lesson b{flex:1;font-weight:400;}
.cur-lesson .dur{flex:none;font-size:12px;color:var(--text-4);}

/* ===== Audience ===== */
.audience-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;}
.aud{background:var(--card);border:1px solid var(--card-border);border-radius:14px;padding:22px;}
.aud .tag{font-size:13px;font-weight:600;color:var(--accent);margin-bottom:8px;}
.aud p{font-size:14px;color:var(--text-2);line-height:1.7;}

/* ===== Instructor ===== */
.instructor{display:flex;gap:28px;align-items:flex-start;background:var(--card);border:1px solid var(--card-border);border-radius:var(--radius);box-shadow:var(--shadow);padding:32px;}
.instructor .avatar{flex:none;width:88px;height:88px;border-radius:50%;display:flex;align-items:center;justify-content:center;color:#fff;font-family:"Space Grotesk";font-weight:700;font-size:30px;}
.avatar.brown{background:linear-gradient(135deg,#B08D57,#8b5cf6);}
.avatar.green{background:linear-gradient(135deg,#22C55E,#0ea5e9);}
.instructor .info{flex:1;}
.instructor h3{font-size:20px;font-weight:700;color:var(--text);}
.instructor .role{font-size:14px;color:var(--accent);font-weight:500;margin:4px 0 12px;}
.instructor p{font-size:14px;color:var(--text-2);line-height:1.8;}
.instructor .tags{display:flex;gap:8px;flex-wrap:wrap;margin-top:14px;}
.instructor .tags span{font-size:12px;color:var(--chip);background:var(--border-soft);padding:5px 10px;border-radius:7px;}

/* ===== Related courses ===== */
.related-row{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;}
.rcard{background:var(--card);border:1px solid var(--card-border);border-radius:var(--radius);box-shadow:var(--shadow);padding:24px;display:flex;flex-direction:column;gap:12px;transition:border-color .2s,transform .2s;}
.rcard:hover{border-color:var(--accent);transform:translateY(-4px);}
.rcard .badge{align-self:flex-start;}
.rcard h3{font-size:18px;font-weight:700;color:var(--text);}
.rcard p{font-size:14px;color:var(--text-3);line-height:1.7;}
.rcard .meta{display:flex;align-items:center;gap:6px;font-size:13px;color:var(--text-3);}
.rcard .meta .dot{width:6px;height:6px;border-radius:50%;background:var(--accent);}
.rcard .go{margin-top:auto;display:flex;align-items:center;gap:6px;font-size:14px;font-weight:500;color:var(--accent);}
.rcard .go .arrow{color:var(--green);font-family:"Inter";font-weight:600;}

/* ===== CTA ===== */
.cta-panel{width:100%;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:16px;text-align:center;padding:56px 40px;background:linear-gradient(90deg,rgba(139,92,246,.28),rgba(34,197,94,.16));border:1px solid var(--line);border-radius:28px;}
.cta-title{font-size:30px;font-weight:700;color:var(--text);}
.cta-sub{font-size:15px;color:var(--text-2);}

/* ===== Footer ===== */
.footer{background:var(--footer);border-top:1px solid var(--line);}
.footer-inner{width:1200px;max-width:calc(100% - 64px);margin:0 auto;padding:48px 0 32px;display:flex;flex-direction:column;gap:24px;}
.footer-top{display:flex;justify-content:space-between;align-items:center;gap:32px;flex-wrap:wrap;}
.footer-brand{display:flex;flex-direction:column;gap:10px;}
.footer-brand p{font-size:13px;color:var(--text-4);max-width:320px;}
.footer-nav{display:flex;gap:24px;font-size:14px;color:var(--text-4);}
.footer-nav a:hover{color:var(--text-2);}
.footer-divider{height:1px;background:var(--line);}
.footer-bottom{display:flex;justify-content:center;font-size:13px;color:var(--text-4);}

/* ===== Responsive ===== */
@media(max-width:900px){
  .hero-grid{grid-template-columns:1fr;gap:32px;}
  .highlights-grid,.audience-grid{grid-template-columns:1fr;}
  .related-row{grid-template-columns:1fr;}
  .nav-links{display:none;}
  .instructor{flex-direction:column;align-items:center;text-align:center;}
  .instructor .tags{justify-content:center;}
}

/* ===== 统一 footer（link-cols，与首页一致） ===== */
.footer-inner{width:1200px;max-width:calc(100% - 64px);margin:0 auto;padding:64px 0 40px;display:flex;flex-direction:column;gap:36px;}
.footer-top{display:flex;justify-content:space-between;gap:48px;flex-wrap:wrap;}
.footer-brand{width:400px;max-width:100%;display:flex;flex-direction:column;gap:16px;}
.footer-brand .logo{font-size:19px;}
.link-cols{display:flex;gap:72px;flex-wrap:wrap;}
.link-col{display:flex;flex-direction:column;gap:14px;}
.link-col b{font-size:15px;font-weight:700;color:var(--text);}
.link-col a{font-size:14px;color:var(--text-4);}
.link-col a:hover{color:var(--text-2);transition:color .2s;}
@media(max-width:1024px){.footer-top{flex-direction:column;}.link-cols{gap:40px;}}

/* ===== 课程正文排版 ===== */
.course-body{max-width:820px;display:flex;flex-direction:column;gap:18px;color:var(--text-2);line-height:1.9;font-size:15px;}
.course-body h2{font-size:24px;font-weight:700;color:var(--text);margin-top:28px;padding-bottom:10px;border-bottom:1px solid var(--line);}
.course-body h2:first-child{margin-top:0;}
.course-body h3{font-size:18px;font-weight:600;color:var(--text);margin-top:22px;}
.course-body h4{font-size:15px;font-weight:600;color:var(--text);margin-top:16px;}
.course-body p{margin:0;}
.course-body ul,.course-body ol{margin:0;padding-left:22px;display:flex;flex-direction:column;gap:8px;}
.course-body ul{list-style:disc;}
.course-body ol{list-style:decimal;}
.course-body li::marker{color:var(--accent);}
.course-body strong{color:var(--text);font-weight:600;}
.course-body a{color:var(--accent);text-decoration:underline;text-underline-offset:3px;}
.course-body code{font-family:"JetBrains Mono","SFMono-Regular",Consolas,monospace;font-size:13px;background:var(--border-soft);border:1px solid var(--line);padding:2px 6px;border-radius:5px;color:var(--code);}
.course-body pre{background:var(--pre-bg);border:1px solid var(--line);border-radius:12px;padding:18px 20px;overflow-x:auto;margin:0;}
.course-body pre code{background:none;border:none;padding:0;color:var(--text);font-size:13px;line-height:1.7;display:block;}
.course-body blockquote{margin:0;padding:14px 18px;border-left:3px solid var(--accent);background:var(--card);border-radius:0 10px 10px 0;color:var(--text-2);}
.course-body blockquote strong{color:var(--text);}
.course-body .callout{display:flex;gap:12px;padding:16px 18px;border-radius:12px;border:1px solid var(--line);background:var(--card);}
.course-body .callout b{color:var(--accent);flex:none;}
.course-body .callout .body{color:var(--text-2);}
.course-body table{width:100%;border-collapse:collapse;font-size:14px;}
.course-body th,.course-body td{text-align:left;padding:10px 14px;border:1px solid var(--line);}
.course-body th{background:var(--card);color:var(--text);font-weight:600;}
.course-body td{color:var(--text-2);}
.course-body hr{border:none;border-top:1px solid var(--line);margin:8px 0;}
@media(max-width:680px){.course-body{font-size:15px;}}

/* ===== 大纲「进入内容」链接 ===== */
.cur-go{padding:14px 0;border-top:1px solid var(--line);}
.cur-go a{display:inline-flex;align-items:center;gap:6px;font-size:14px;font-weight:600;color:var(--accent);}
.cur-go a:hover{opacity:.85;}

/* ===== 模块内容页导航 ===== */
.module-nav{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-bottom:24px;}
.module-nav-item{display:flex;flex-direction:column;gap:6px;padding:20px 22px;border:1px solid var(--card-border);border-radius:14px;background:var(--card);}
.module-nav-item:hover{border-color:var(--accent);}
.module-nav-item.prev{text-align:left;}
.module-nav-item.next{text-align:right;}
.module-nav-item .nav-label{font-size:12px;color:var(--text-4);}
.module-nav-item .nav-title{font-size:15px;font-weight:600;color:var(--text);}
.module-nav-item.is-empty{opacity:.4;pointer-events:none;}
.module-cta{display:flex;justify-content:center;}
@media(max-width:680px){.module-nav{grid-template-columns:1fr;}}