:root { color-scheme: light; --ink:#172026; --muted:#52616b; --line:#d9e2ec; --soft:#f5f7fa; --paper:#ffffff; --accent:#0f766e; --accent-strong:#115e59; --accent-soft:#e7f5f2; --warm:#b45309; --warm-soft:#fff7ed; --mark:#0b3b3a; --warn:#7c2d12; }
* { box-sizing: border-box; }
body { margin:0; font-family: Arial, Helvetica, sans-serif; color:var(--ink); background:#fbfcfd; line-height:1.58; }
body::before { content:""; display:block; height:7px; background:linear-gradient(90deg, var(--accent) 0 58%, var(--warm) 58% 78%, var(--ink) 78% 100%); }
a { color:var(--accent); font-weight:700; text-decoration:none; }
a:hover { text-decoration:underline; }
.topbar { position:sticky; top:0; z-index:10; background:#ffffffee; backdrop-filter:blur(10px); border-bottom:1px solid var(--line); box-shadow:0 10px 30px rgba(23,32,38,.05); padding:10px 22px; display:flex; align-items:center; justify-content:space-between; gap:16px; }
.brand { display:flex; align-items:center; gap:10px; color:var(--ink); }
.brand img { width:76px; height:auto; display:block; }
.topbar nav { display:flex; gap:14px; }
.topbar span { color:#9aa5b1; font-weight:700; }
.site-hero { max-width:1180px; margin:0 auto; padding:58px 22px 42px; display:grid; grid-template-columns:minmax(0, 1fr) 300px; gap:34px; align-items:end; position:relative; }
.site-hero::after { content:"20"; position:absolute; right:22px; top:20px; z-index:-1; color:#edf3f2; font-size:172px; line-height:.8; font-weight:700; letter-spacing:0; }
.home { max-width:1180px; margin:0 auto; padding:16px 22px 72px; }
.page-shell { max-width:1180px; margin:0 auto; padding:34px 22px 72px; display:grid; grid-template-columns:230px minmax(0, 1fr); gap:34px; align-items:start; }
.page { min-width:0; background:var(--paper); border:1px solid var(--line); border-radius:8px; box-shadow:0 18px 46px rgba(23,32,38,.06); padding:34px 42px 46px; }
.rail { position:sticky; top:86px; background:linear-gradient(180deg,#ffffff 0%,#f8fafc 100%); border:1px solid var(--line); border-top:4px solid var(--accent); border-radius:8px; padding:18px; }
.rail p { margin:18px 0 4px; color:var(--muted); font-size:13px; text-transform:uppercase; font-weight:700; }
.rail strong { display:block; font-size:15px; line-height:1.35; }
.project-logo { width:min(410px, 100%); height:auto; display:block; margin:0 0 22px; filter:drop-shadow(0 18px 28px rgba(15,118,110,.12)); }
.eyebrow { text-transform:uppercase; font-size:13px; letter-spacing:.08em; color:var(--accent); font-weight:700; margin:0 0 10px; }
h1 { font-size:38px; line-height:1.12; margin:0 0 18px; max-width:850px; }
h2 { font-size:24px; margin:32px 0 12px; }
h3 { font-size:19px; margin:26px 0 8px; }
p, li { font-size:16px; }
.lead { max-width:720px; color:var(--muted); font-size:18px; margin-bottom:28px; }
.hero-panel { border:1px solid #b8d8d4; background:linear-gradient(180deg,#ffffff 0%,#eef8f6 100%); border-radius:8px; padding:22px; display:grid; gap:10px; box-shadow:0 22px 44px rgba(15,118,110,.12); }
.hero-panel strong { font-size:34px; line-height:1; color:var(--mark); }
.hero-panel span { color:var(--ink); border-top:1px solid #cfe7e3; padding-top:9px; }
.section-head { border-top:1px solid var(--line); padding-top:24px; margin-top:8px; }
.course-grid { display:grid; grid-template-columns:repeat(2, minmax(0, 1fr)); gap:14px; margin-top:18px; }
.course-card { min-height:108px; display:grid; grid-template-columns:54px 1fr; grid-template-rows:auto auto; gap:7px 16px; align-items:start; border:1px solid var(--line); border-radius:8px; background:var(--paper); padding:17px; color:var(--ink); box-shadow:0 10px 24px rgba(23,32,38,.04); transition:transform .16s ease, box-shadow .16s ease, border-color .16s ease; }
.course-card:hover { border-color:var(--accent); text-decoration:none; background:#f8fffd; transform:translateY(-2px); box-shadow:0 16px 34px rgba(15,118,110,.12); }
.course-card span { width:42px; height:42px; border-radius:50%; display:grid; place-items:center; background:var(--accent-soft); color:var(--accent-strong); font-weight:700; font-size:14px; }
.course-card:nth-child(4n) span, .course-card:nth-child(4n-1) span { background:var(--warm-soft); color:var(--warm); }
.course-card strong { line-height:1.35; }
.course-card em { grid-column:2; color:var(--muted); font-size:13px; font-style:normal; font-weight:700; text-transform:uppercase; letter-spacing:.06em; }
.source-card { margin-top:26px; border:1px solid #b8d8d4; border-left:6px solid var(--warm); background:linear-gradient(90deg,#ffffff 0%,#fffaf5 100%); border-radius:8px; padding:22px; box-shadow:0 12px 30px rgba(23,32,38,.05); }
.source-card h2 { margin-top:0; }
.source-card p { color:var(--muted); max-width:820px; }
.content-block, .question, .video-note, .materials, .materials-summary, .video-card { border-top:1px solid var(--line); padding-top:20px; margin-top:24px; }
.content-block img { max-width:100%; height:auto; display:block; margin:18px 0; }
.question { background:#f8fafc; border:1px solid var(--line); border-left:5px solid var(--accent); border-radius:8px; padding:18px 20px; }
.prompt { font-weight:700; }
.options { margin-bottom:0; }
.correct-option { font-weight:700; color:#0f5132; }
.solution { margin-top:16px; padding:14px 16px; border:1px solid #b8d8d4; border-left:5px solid var(--warm); background:#fffaf5; border-radius:8px; }
.solution h4 { margin:0 0 8px; font-size:16px; }
.solution p { margin:6px 0; }
.video-note { color:var(--muted); }
.materials-summary { background:#f8fafc; border:1px solid var(--line); border-top:4px solid var(--accent); border-radius:8px; padding:18px 20px; }
.materials-summary h2 { margin-top:0; }
.quick-links { padding-left:20px; }
.quick-links li { margin:12px 0; }
.quick-links span { display:block; font-weight:700; margin-bottom:4px; }
.quick-links a { display:inline-block; margin-right:12px; }
.media-item { margin:18px 0 26px; }
.media-item video, .video-card video { width:100%; max-height:520px; background:#0b1220; border-radius:8px; display:block; }
.video-frame { position:relative; width:100%; aspect-ratio:16 / 9; background:#0b1220; border-radius:8px; overflow:hidden; }
.video-frame iframe { position:absolute; inset:0; width:100%; height:100%; border:0; }
.youtube-open { display:flex; align-items:center; justify-content:center; min-height:170px; border-radius:8px; background:linear-gradient(135deg,#172026 0%,#0f3f3b 100%); color:white; font-size:20px; text-align:center; padding:24px; box-shadow:inset 0 0 0 1px rgba(255,255,255,.08); }
.youtube-open:hover { color:white; text-decoration:underline; }
.media-item p, .video-card p, .material-list span { color:var(--muted); font-size:14px; }
.caption-note { margin-top:8px; }
.material-list { padding-left:22px; }
.material-list li { margin:10px 0; }
footer, .source { max-width:980px; margin:0 auto; padding:18px 22px 36px; color:var(--muted); font-size:13px; border-top:1px solid var(--line); }
@media (max-width: 820px) {
  .site-hero, .page-shell { display:block; }
  .hero-panel, .rail { margin-top:18px; position:static; }
  .page { padding:26px 20px 34px; margin-top:18px; }
  .course-grid { grid-template-columns:1fr; }
  h1 { font-size:31px; }
  .topbar { padding:10px 14px; }
  .brand img { width:64px; }
}