:root {
  --ink: #0b1424;
  --navy: #081426;
  --navy-2: #11213a;
  --paper: #f3f6fb;
  --white: #ffffff;
  --muted: #68758a;
  --line: #dce3ee;
  --lime: #d9ff45;
  --blue: #2f66ff;
  --cyan: #22c7b8;
  --orange: #ff8c42;
  --violet: #8157ff;
  --radius: 18px;
  --shadow: 0 18px 45px rgba(15, 31, 57, .09);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, "SF Pro Display", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}
button, input { font: inherit; }
a { color: inherit; }
.skip-link { position: fixed; left: 16px; top: -60px; z-index: 100; padding: 10px 14px; background: var(--lime); color: var(--navy); border-radius: 8px; }
.skip-link:focus { top: 16px; }

.app-shell { min-height: 100vh; display: grid; grid-template-columns: 250px minmax(0, 1fr); }
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 30;
  width: 250px;
  display: flex;
  flex-direction: column;
  padding: 26px 18px 22px;
  background: var(--navy);
  color: #eaf0fb;
}
.brand { display: flex; gap: 12px; align-items: center; padding: 0 8px 28px; text-decoration: none; }
.brand-mark { width: 44px; height: 44px; display: grid; place-items: center; border-radius: 12px; background: var(--lime); color: var(--navy); font-weight: 900; letter-spacing: -.05em; }
.brand strong { display: block; font-size: 1.12rem; letter-spacing: .02em; }
.brand small { display: block; margin-top: 1px; color: #7f90aa; font-size: .7rem; letter-spacing: .18em; }
.nav-list { display: grid; gap: 7px; }
.nav-link { display: flex; align-items: center; gap: 12px; padding: 12px 14px; border-radius: 11px; color: #9fadc1; text-decoration: none; font-weight: 650; }
.nav-link span { width: 22px; text-align: center; font-size: 1.1rem; }
.nav-link:hover, .nav-link.active { background: #182943; color: #fff; }
.nav-link.active { box-shadow: inset 3px 0 0 var(--lime); }
.sidebar-note { margin-top: auto; padding: 16px; border: 1px solid #263a58; border-radius: 14px; background: #0d1c31; }
.sidebar-note span { color: var(--lime); font-weight: 750; }
.sidebar-note p { margin: 7px 0 0; color: #92a2ba; font-size: .82rem; line-height: 1.55; }

.workspace { grid-column: 2; min-width: 0; }
.topbar { position: sticky; top: 0; z-index: 20; height: 78px; display: flex; align-items: center; justify-content: space-between; gap: 20px; padding: 0 4.2vw; border-bottom: 1px solid rgba(220, 227, 238, .9); background: rgba(243, 246, 251, .92); backdrop-filter: blur(16px); }
.search-box { width: min(560px, 58vw); display: flex; align-items: center; gap: 10px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--white); color: var(--muted); }
.search-box:focus-within { border-color: var(--blue); box-shadow: 0 0 0 3px rgba(47,102,255,.12); }
.search-box input { width: 100%; min-width: 0; border: 0; outline: 0; color: var(--ink); background: transparent; }
.search-box kbd { padding: 2px 7px; border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 6px; color: #8b97a8; font-size: .72rem; }
.topbar-meta { display: flex; align-items: center; gap: 8px; color: var(--muted); font-size: .86rem; white-space: nowrap; }
.live-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--cyan); box-shadow: 0 0 0 5px rgba(34,199,184,.12); }
.mobile-menu { display: none; border: 0; background: transparent; font-size: 1.4rem; }

#main { padding: 42px 4.2vw 64px; }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; color: var(--blue); font-size: .78rem; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; }
.eyebrow::before { content: ""; width: 22px; height: 2px; background: currentColor; }
h1, h2, h3 { margin-top: 0; line-height: 1.25; letter-spacing: -.025em; }
h1 { margin-bottom: 12px; font-size: clamp(2rem, 4vw, 3.75rem); }
h2 { font-size: clamp(1.35rem, 2vw, 1.8rem); }
p { color: var(--muted); }
.page-head { display: flex; align-items: end; justify-content: space-between; gap: 24px; margin-bottom: 30px; }
.page-head h1 { margin: 8px 0 6px; font-size: clamp(2rem, 3.1vw, 3.1rem); }
.page-head p { max-width: 720px; margin: 0; }
.course-count { min-width: 112px; padding: 14px 18px; border-left: 3px solid var(--lime); background: var(--navy); color: #fff; }
.course-count strong { display: block; font-size: 1.55rem; }
.course-count span { color: #99a9bf; font-size: .78rem; }

.spotlight { position: relative; overflow: hidden; display: grid; grid-template-columns: 1.3fr .8fr; min-height: 310px; margin-bottom: 42px; border-radius: 24px; background: var(--navy); color: #fff; box-shadow: var(--shadow); }
.spotlight::after { content: ""; position: absolute; right: -70px; top: -90px; width: 310px; height: 310px; border: 1px solid rgba(217,255,69,.28); border-radius: 50%; box-shadow: 0 0 0 55px rgba(217,255,69,.04), 0 0 0 110px rgba(217,255,69,.025); }
.spotlight-copy { position: relative; z-index: 2; align-self: center; padding: 40px; }
.spotlight .eyebrow { color: var(--lime); }
.spotlight h2 { max-width: 650px; margin: 14px 0; font-size: clamp(1.8rem, 3.1vw, 3rem); }
.spotlight p { max-width: 600px; color: #a9b7cb; }
.primary-btn, .secondary-btn, .text-btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 44px; border-radius: 10px; text-decoration: none; font-weight: 800; cursor: pointer; }
.primary-btn { padding: 11px 18px; border: 1px solid var(--lime); background: var(--lime); color: var(--navy); }
.primary-btn:hover { transform: translateY(-1px); box-shadow: 0 8px 20px rgba(217,255,69,.16); }
.secondary-btn { padding: 10px 16px; border: 1px solid var(--line); background: #fff; color: var(--ink); }
.text-btn { min-height: auto; color: var(--blue); }
.spotlight-map { position: relative; z-index: 2; display: grid; align-content: center; gap: 12px; padding: 36px 42px 36px 0; }
.map-step { display: grid; grid-template-columns: 34px 1fr; gap: 12px; align-items: center; color: #c5d0df; }
.map-step b { width: 34px; height: 34px; display: grid; place-items: center; border-radius: 50%; border: 1px solid #40516a; color: var(--lime); }
.map-step span { height: 1px; background: linear-gradient(90deg, #36485f, transparent); }

.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 20px; margin: 34px 0 18px; }
.section-heading h2 { margin-bottom: 3px; }
.section-heading p { margin: 0; }
.course-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.course-card { position: relative; overflow: hidden; min-height: 290px; display: flex; flex-direction: column; padding: 24px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--white); box-shadow: 0 4px 16px rgba(15,31,57,.035); transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease; }
.course-card:hover { transform: translateY(-4px); border-color: #bac6d8; box-shadow: var(--shadow); }
.course-card::before { content: ""; position: absolute; inset: 0 0 auto 0; height: 5px; background: var(--accent, var(--blue)); }
.course-top { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.course-icon { width: 48px; height: 48px; display: grid; place-items: center; border-radius: 14px; background: color-mix(in srgb, var(--accent, var(--blue)) 12%, white); color: var(--accent, var(--blue)); font-size: 1.35rem; font-weight: 900; }
.course-label { padding: 4px 9px; border-radius: 999px; background: #f2f5fa; color: var(--muted); font-size: .72rem; font-weight: 800; }
.course-card h3 { margin: 20px 0 9px; font-size: 1.24rem; }
.course-card p { flex: 1; margin: 0 0 22px; font-size: .92rem; }
.course-meta { display: flex; justify-content: space-between; gap: 12px; padding-top: 16px; border-top: 1px solid #edf1f6; color: var(--muted); font-size: .8rem; }
.course-meta strong { color: var(--ink); }
.empty-state { grid-column: 1 / -1; padding: 48px; border: 1px dashed #b8c3d4; border-radius: var(--radius); text-align: center; background: #fff; }

.path-strip { display: grid; grid-template-columns: repeat(6, 1fr); margin-top: 42px; border: 1px solid var(--line); border-radius: var(--radius); background: #fff; overflow: hidden; }
.path-item { position: relative; padding: 22px 18px; border-right: 1px solid var(--line); text-decoration: none; transition: background .18s ease; }
.path-item:hover { background: #f7faff; }
.path-item:last-child { border-right: 0; }
.path-item b { display: block; margin-bottom: 5px; font-size: .84rem; color: var(--blue); }
.path-item span { display: block; font-weight: 750; font-size: .9rem; line-height: 1.4; }

.course-hero { position: relative; overflow: hidden; padding: 38px; border-radius: 24px; background: var(--navy); color: white; }
.course-hero::after { content: attr(data-index); position: absolute; right: 28px; bottom: -42px; color: rgba(255,255,255,.045); font-size: 13rem; font-weight: 950; line-height: 1; }
.back-link { display: inline-flex; margin-bottom: 22px; color: #a8b6c9; text-decoration: none; font-weight: 700; }
.back-link:hover { color: white; }
.course-hero .eyebrow { color: var(--accent, var(--lime)); }
.course-hero h1 { position: relative; z-index: 2; max-width: 820px; margin: 12px 0; }
.course-hero p { position: relative; z-index: 2; max-width: 720px; color: #aebbcf; font-size: 1.04rem; }
.hero-meta { position: relative; z-index: 2; display: flex; flex-wrap: wrap; gap: 18px; margin-top: 24px; color: #dce5f2; font-size: .88rem; }
.hero-meta span { padding-right: 18px; border-right: 1px solid #334760; }
.hero-meta span:last-child { border-right: 0; }

.course-layout { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 26px; margin-top: 26px; align-items: start; }
.lesson-list { display: grid; gap: 16px; }
.lesson { scroll-margin-top: 98px; border: 1px solid var(--line); border-radius: 16px; background: #fff; overflow: hidden; }
.lesson summary { list-style: none; display: grid; grid-template-columns: 52px 1fr auto; gap: 16px; align-items: center; padding: 20px 22px; cursor: pointer; }
.lesson summary::-webkit-details-marker { display: none; }
.lesson summary:hover { background: #f9fbfe; }
.lesson-number { width: 42px; height: 42px; display: grid; place-items: center; border-radius: 12px; background: #edf2f8; color: var(--blue); font-weight: 900; }
.lesson-title strong { display: block; }
.lesson-title span { display: block; color: var(--muted); font-size: .84rem; }
.lesson summary::after { content: "+"; color: var(--muted); font-size: 1.35rem; }
.lesson[open] summary::after { content: "−"; }
.lesson-body { padding: 0 24px 24px 90px; border-top: 1px solid #edf1f6; }
.lesson-body h4 { margin: 22px 0 8px; font-size: 1rem; }
.lesson-body p { margin: 8px 0; }
.lesson-body ul { margin: 10px 0; padding-left: 20px; color: #344158; }
.lesson-body li { margin: 6px 0; }
.lesson-body > p:first-child { margin-top: 20px; font-size: 1.02rem; color: #3c4b61; }
.takeaway { margin-top: 22px; padding: 16px 18px; border-left: 4px solid var(--lime); border-radius: 0 12px 12px 0; background: #f8fce8; }
.takeaway strong { color: #3e5110; }
.takeaway p { margin: 4px 0 0; color: #4f6025; }
.flow-row { display: flex; gap: 8px; align-items: stretch; overflow-x: auto; margin: 20px 0; padding: 4px 2px 10px; }
.flow-row span { display: flex; align-items: center; gap: 8px; min-width: max-content; padding: 9px 11px; border-radius: 9px; background: #eef4ff; color: #24477f; font-size: .85rem; font-weight: 750; }
.flow-row i { color: #87a0c3; font-style: normal; }
.step-list { counter-reset: learning-step; display: grid; gap: 10px; margin: 18px 0; padding: 0; list-style: none; }
.step-list li { counter-increment: learning-step; display: grid; grid-template-columns: 30px 1fr; gap: 10px; align-items: start; margin: 0; color: #344158; }
.step-list li::before { content: counter(learning-step); width: 28px; height: 28px; display: grid; place-items: center; border-radius: 50%; background: var(--navy); color: #fff; font-size: .76rem; font-weight: 850; }
.check-list { display: grid; gap: 9px; padding: 0 !important; list-style: none; }
.check-list li { position: relative; margin: 0; padding: 10px 12px 10px 38px; border: 1px solid #e0e8f1; border-radius: 10px; background: #fbfcfe; }
.check-list li::before { content: "✓"; position: absolute; left: 12px; top: 9px; color: #0f9f78; font-weight: 900; }
.table-wrap { overflow-x: auto; margin: 20px 0; border: 1px solid var(--line); border-radius: 12px; }
.table-wrap table { width: 100%; min-width: 560px; border-collapse: collapse; font-size: .86rem; }
.table-wrap th { padding: 11px 13px; background: var(--navy); color: #fff; text-align: left; }
.table-wrap td { padding: 11px 13px; border-top: 1px solid var(--line); color: #3c4b61; vertical-align: top; }
.table-wrap tr:nth-child(even) td { background: #f8fafd; }
.template-box { margin-top: 20px; padding: 16px; border: 1px solid #d8e2f0; border-radius: 12px; background: #f7faff; }
.template-box > strong { display: block; margin-bottom: 10px; }
.template-box div { display: flex; flex-wrap: wrap; gap: 8px; }
.template-box span { padding: 5px 9px; border: 1px solid #cedbec; border-radius: 999px; background: #fff; color: #40536e; font-size: .78rem; font-weight: 700; }
.process-map { display: grid; grid-template-columns: repeat(3, minmax(210px, 1fr)); gap: 12px; margin: 20px 0; }
.process-node { position: relative; min-height: 142px; padding: 16px; border: 1px solid #d9e2ef; border-radius: 13px; background: #f9fbfe; }
.process-node > div { display: flex; align-items: center; gap: 9px; }
.process-node b { padding: 3px 7px; border-radius: 6px; background: var(--navy); color: var(--lime); font-size: .72rem; }
.process-node strong { font-size: .96rem; }
.process-node small { display: block; margin-top: 9px; color: var(--blue); font-weight: 750; }
.process-node p { margin: 6px 0 0; font-size: .8rem; line-height: 1.5; }
.process-node > span { position: absolute; right: -11px; top: 52%; z-index: 2; width: 20px; height: 20px; display: grid; place-items: center; border-radius: 50%; background: var(--lime); color: var(--navy); font-size: .7rem; font-weight: 900; }
.lesson-nav { display: flex; justify-content: space-between; gap: 12px; margin-top: 26px; padding-top: 18px; border-top: 1px solid #e5ebf3; }
.lesson-nav-btn { min-height: 42px; padding: 10px 14px; border: 1px solid var(--line); border-radius: 9px; background: #fff; color: var(--ink); text-decoration: none; cursor: pointer; font-weight: 750; }
.lesson-nav-btn.next { margin-left: auto; border-color: var(--navy); background: var(--navy); color: #fff; }
.lesson-nav-btn:hover { transform: translateY(-1px); }
.resource-link { display: inline-flex; align-items: center; gap: 10px; margin-top: 12px; padding: 11px 15px; border-radius: 10px; background: var(--navy); color: #fff; text-decoration: none; font-weight: 800; }
.resource-link::before { content: "↗"; width: 25px; height: 25px; display: grid; place-items: center; border-radius: 50%; background: var(--lime); color: var(--navy); font-size: .8rem; }
.video-player { margin: 24px 0 0; }
.video-frame { position: relative; overflow: hidden; aspect-ratio: 16 / 9; border-radius: 14px; background: #030812; box-shadow: 0 14px 34px rgba(6, 17, 34, .18); }
.video-frame video { width: 100%; height: 100%; display: block; background: #030812; object-fit: contain; }
.video-player figcaption { display: flex; align-items: center; gap: 10px; margin-top: 10px; color: var(--muted); font-size: .82rem; }
.video-player figcaption span { padding: 3px 8px; border-radius: 999px; background: #e9f0ff; color: var(--blue); font-weight: 800; }
.video-player figcaption p { margin: 0; }
.video-error { margin: 10px 0 0 !important; padding: 10px 12px; border: 1px solid #f0c8b6; border-radius: 9px; background: #fff5f0; color: #9a4521 !important; font-size: .84rem; }
.course-aside { position: sticky; top: 104px; display: grid; gap: 16px; }
.aside-card { padding: 20px; border: 1px solid var(--line); border-radius: 16px; background: #fff; }
.aside-card h3 { margin-bottom: 12px; font-size: 1rem; }
.outline-list { display: grid; gap: 2px; }
.outline-list button { width: 100%; display: grid; grid-template-columns: 24px 1fr; gap: 8px; padding: 8px 0; border: 0; background: transparent; color: #4f5e74; text-align: left; cursor: pointer; font-size: .84rem; }
.outline-list button:hover { color: var(--blue); }
.outline-list b { color: #9ca8b8; }
.source-note { margin: 0; font-size: .82rem; }
.privacy-note { border-color: #d7e3bb; background: #fbffef; }
.privacy-note strong { display: block; margin-bottom: 5px; color: #485d12; }

.category-tabs { display: flex; gap: 9px; flex-wrap: wrap; margin-bottom: 24px; }
.category-tabs a { padding: 8px 13px; border: 1px solid var(--line); border-radius: 999px; background: #fff; color: var(--muted); text-decoration: none; font-size: .84rem; font-weight: 750; }
.category-tabs a.active { background: var(--navy); border-color: var(--navy); color: #fff; }

.backdrop { position: fixed; inset: 0; z-index: 25; background: rgba(1,8,19,.48); }

@media (max-width: 1120px) {
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .path-strip { grid-template-columns: repeat(3, 1fr); }
  .path-item:nth-child(3) { border-right: 0; }
  .path-item:nth-child(-n+3) { border-bottom: 1px solid var(--line); }
}

@media (max-width: 900px) {
  .app-shell { display: block; }
  .workspace { grid-column: auto; }
  .sidebar { transform: translateX(-102%); transition: transform .22s ease; box-shadow: 16px 0 50px rgba(3,10,22,.22); }
  body.menu-open .sidebar { transform: translateX(0); }
  .mobile-menu { display: block; }
  .search-box { width: min(520px, 68vw); }
  .topbar-meta { display: none; }
  .spotlight { grid-template-columns: 1fr; }
  .spotlight-map { grid-template-columns: repeat(5, 1fr); padding: 0 32px 32px; }
  .map-step { grid-template-columns: 1fr; justify-items: center; text-align: center; font-size: .76rem; }
  .map-step span { display: none; }
  .course-layout { grid-template-columns: 1fr; }
  .course-aside { position: static; grid-template-columns: 1fr 1fr; }
}

@media (max-width: 650px) {
  #main { padding: 28px 18px 50px; }
  .topbar { height: 68px; padding: 0 16px; }
  .search-box { flex: 1; width: auto; }
  .search-box kbd { display: none; }
  .page-head { align-items: start; }
  .course-count { display: none; }
  .spotlight-copy { padding: 30px 24px; }
  .spotlight-map { grid-template-columns: 1fr; padding: 0 24px 28px; }
  .map-step { grid-template-columns: 34px 1fr; justify-items: start; text-align: left; }
  .map-step span { display: block; }
  .course-grid { grid-template-columns: 1fr; }
  .path-strip { grid-template-columns: 1fr 1fr; }
  .path-item, .path-item:nth-child(3) { border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
  .path-item:nth-child(even) { border-right: 0; }
  .path-item:nth-last-child(-n+2) { border-bottom: 0; }
  .course-hero { padding: 28px 22px; }
  .course-hero::after { display: none; }
  .lesson summary { grid-template-columns: 42px 1fr auto; padding: 16px; }
  .lesson-body { padding: 0 18px 20px; }
  .course-aside { grid-template-columns: 1fr; }
  .process-map { grid-template-columns: 1fr; }
  .process-node > span { right: 50%; top: auto; bottom: -11px; transform: translateX(50%) rotate(90deg); }
  .lesson-nav { align-items: stretch; flex-direction: column; }
  .lesson-nav-btn, .lesson-nav-btn.next { width: 100%; margin-left: 0; text-align: center; }
  .video-player figcaption { align-items: flex-start; flex-direction: column; gap: 5px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}