:root {
  --ptv-navy: #10283a;
  --ptv-navy-deep: #081a29;
  --ptv-blue: #147da0;
  --ptv-cyan: #5bd4db;
  --ptv-amber: #f2b84b;
  --ptv-ink: #132535;
  --ptv-muted: #5e6d79;
  --ptv-line: #dbe4e8;
  --ptv-soft: #f2f7f8;
  --ptv-paper: #ffffff;
  --ptv-shadow: 0 18px 48px rgba(16, 40, 58, 0.11);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: #f7f9f9;
  color: var(--ptv-ink);
  font-family: "DM Sans", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.65;
}
a { color: inherit; }
img { display: block; max-width: 100%; }
.page-shell { width: min(1180px, calc(100% - 44px)); margin-inline: auto; }
.skip-link { position: fixed; top: 8px; left: 8px; z-index: 100; padding: 10px 14px; background: #fff; color: #000; transform: translateY(-150%); }
.skip-link:focus { transform: none; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid rgba(255,255,255,.1);
  background: rgba(8, 26, 41, .94);
  backdrop-filter: blur(12px);
}
.nav-shell { width: min(1180px, calc(100% - 44px)); min-height: 68px; margin-inline: auto; display: flex; align-items: center; gap: 28px; }
.brand { display: inline-flex; align-items: center; gap: 10px; color: #fff; font-weight: 800; text-decoration: none; white-space: nowrap; }
.brand-mark { display: grid; width: 35px; height: 35px; place-items: center; border: 1px solid rgba(255,255,255,.65); border-radius: 9px; font-size: .78rem; }
.main-nav { display: flex; align-items: center; gap: 24px; margin-left: auto; }
.main-nav a { color: #c9d7df; font-size: .94rem; font-weight: 600; text-decoration: none; }
.main-nav a:hover, .main-nav a.active { color: #fff; }
.nav-cta { padding: 9px 15px; border-radius: 999px; background: var(--ptv-cyan); color: #092232; font-weight: 800; text-decoration: none; }

.hero {
  overflow: hidden;
  padding: 74px 0 68px;
  color: #fff;
  background:
    radial-gradient(circle at 90% 0, rgba(91,212,219,.22), transparent 31%),
    radial-gradient(circle at 10% 90%, rgba(20,125,160,.28), transparent 36%),
    linear-gradient(130deg, var(--ptv-navy-deep), var(--ptv-navy));
}
.hero-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(400px, .86fr); gap: 62px; align-items: center; }
.eyebrow, .kicker { margin: 0 0 14px; color: var(--ptv-cyan); font-size: .78rem; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; }
.eyebrow { display: flex; align-items: center; gap: 10px; }
.eyebrow::before { content: ""; width: 24px; height: 2px; background: var(--ptv-amber); }
.hero h1 { max-width: 720px; margin: 0 0 22px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(2.7rem, 5.2vw, 5rem); font-weight: 500; line-height: 1.01; letter-spacing: -.045em; }
.hero h1 span { color: var(--ptv-cyan); }
.hero-lede { max-width: 720px; margin: 0 0 28px; color: #d6e2e8; font-size: 1.12rem; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 9px; min-height: 48px; padding: 11px 18px; border: 1px solid transparent; border-radius: 999px; font-weight: 800; text-decoration: none; transition: transform .18s ease, background .18s ease; }
.button:hover { transform: translateY(-2px); }
.button-primary { background: var(--ptv-cyan); color: #092232; }
.button-secondary { border-color: rgba(255,255,255,.36); color: #fff; background: rgba(255,255,255,.04); }
.button-dark { background: var(--ptv-navy); color: #fff; }
.button-light { border-color: var(--ptv-line); background: #fff; color: var(--ptv-ink); }
.course-status { display: flex; flex-wrap: wrap; gap: 16px 26px; margin: 30px 0 0; padding: 25px 0 0; border-top: 1px solid rgba(255,255,255,.16); list-style: none; }
.course-status strong { display: block; color: #fff; font-size: 1.05rem; }
.course-status span { color: #9fb3bf; font-size: .88rem; }

.playlist-card { padding: 14px; border: 1px solid rgba(255,255,255,.22); border-radius: 22px; background: rgba(255,255,255,.09); box-shadow: 0 28px 65px rgba(0,0,0,.24); }
.playlist-frame { position: relative; overflow: hidden; aspect-ratio: 16 / 9; border-radius: 15px; background: #000; }
.playlist-frame iframe { width: 100%; height: 100%; border: 0; }
.playlist-meta { display: flex; align-items: center; justify-content: space-between; gap: 18px; padding: 17px 5px 4px; }
.playlist-meta strong { display: block; font-size: 1rem; }
.playlist-meta span { color: #b7cad4; font-size: .88rem; }
.lesson-count { flex: 0 0 auto; padding: 6px 11px; border-radius: 999px; background: rgba(91,212,219,.15); color: var(--ptv-cyan)!important; font-weight: 800; }

.section-nav { border-bottom: 1px solid var(--ptv-line); background: #fff; }
.section-nav .page-shell { display: flex; gap: 26px; overflow-x: auto; padding-block: 15px; white-space: nowrap; }
.section-nav span { font-weight: 800; color: var(--ptv-navy); }
.section-nav a { color: var(--ptv-muted); font-size: .93rem; font-weight: 700; text-decoration: none; }
.section { padding: 82px 0; }
.section-alt { background: var(--ptv-soft); }
.section-heading { max-width: 790px; margin-bottom: 35px; }
.section-heading h2 { margin: 0 0 12px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(2rem, 4vw, 3.45rem); font-weight: 500; line-height: 1.08; letter-spacing: -.035em; }
.section-heading p { margin: 0; color: var(--ptv-muted); font-size: 1.05rem; }
.kicker { color: var(--ptv-blue); }

.definition-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 22px; }
.definition-card { position: relative; overflow: hidden; padding: 30px; border: 1px solid var(--ptv-line); border-radius: 20px; background: #fff; box-shadow: var(--ptv-shadow); }
.definition-card::after { content: ""; position: absolute; width: 125px; height: 125px; right: -45px; bottom: -55px; border-radius: 50%; background: rgba(91,212,219,.14); }
.definition-card .number { color: var(--ptv-blue); font-size: .82rem; font-weight: 900; letter-spacing: .12em; }
.definition-card h3 { margin: 12px 0 10px; font-family: Georgia, "Times New Roman", serif; font-size: 1.65rem; font-weight: 500; }
.definition-card p { margin: 0; color: var(--ptv-muted); }
.definition-card ul { margin: 18px 0 0; padding-left: 20px; }
.definition-card li + li { margin-top: 7px; }
.plain-note { margin: 24px 0 0; padding: 17px 20px; border-left: 4px solid var(--ptv-amber); border-radius: 0 12px 12px 0; background: #fff9eb; color: #5e4a25; }

.roadmap { display: grid; gap: 15px; margin: 0; padding: 0; list-style: none; counter-reset: lesson; }
.roadmap li { display: grid; grid-template-columns: 72px minmax(0, 1fr) auto; gap: 20px; align-items: center; padding: 23px; border: 1px solid var(--ptv-line); border-radius: 17px; background: #fff; }
.module-number { display: grid; width: 58px; height: 58px; place-items: center; border-radius: 17px; background: var(--ptv-navy); color: var(--ptv-cyan); font-weight: 900; }
.roadmap h3 { margin: 0 0 5px; font-size: 1.12rem; }
.roadmap p { margin: 0; color: var(--ptv-muted); }
.status { padding: 7px 12px; border-radius: 999px; font-size: .78rem; font-weight: 900; text-transform: uppercase; letter-spacing: .06em; }
.status-live { background: #e5f8f4; color: #087460; }
.status-next { background: #eef1f3; color: #64717a; }

.video-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
.video-card { overflow: hidden; border: 1px solid var(--ptv-line); border-radius: 20px; background: #fff; box-shadow: var(--ptv-shadow); }
.video-thumb { position: relative; display: block; overflow: hidden; aspect-ratio: 16 / 9; background: #152333; }
.video-thumb img { width: 100%; height: 100%; object-fit: cover; transition: transform .25s ease, filter .25s ease; }
.video-thumb:hover img { transform: scale(1.025); filter: brightness(.78); }
.play-button { position: absolute; inset: 50% auto auto 50%; display: grid; width: 72px; height: 50px; place-items: center; border-radius: 14px; background: #ff0033; color: #fff; font-size: 1.35rem; transform: translate(-50%, -50%); box-shadow: 0 10px 25px rgba(0,0,0,.35); }
.duration { position: absolute; right: 12px; bottom: 12px; padding: 4px 8px; border-radius: 6px; background: rgba(0,0,0,.84); color: #fff; font-size: .76rem; font-weight: 800; }
.video-body { padding: 23px; }
.video-body .part { color: var(--ptv-blue); font-size: .76rem; font-weight: 900; letter-spacing: .1em; text-transform: uppercase; }
.video-body h3 { margin: 8px 0 9px; font-size: 1.22rem; line-height: 1.3; }
.video-body p { margin: 0 0 16px; color: var(--ptv-muted); }
.text-link { color: var(--ptv-blue); font-weight: 800; text-decoration: none; }
.text-link:hover { text-decoration: underline; }

.workflow-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.workflow-card { padding: 23px; border-top: 4px solid var(--ptv-cyan); border-radius: 4px 15px 15px 15px; background: #fff; }
.workflow-card:nth-child(2n) { border-top-color: var(--ptv-amber); }
.workflow-card span { color: var(--ptv-blue); font-size: .78rem; font-weight: 900; }
.workflow-card h3 { margin: 8px 0; font-size: 1.08rem; }
.workflow-card p { margin: 0; color: var(--ptv-muted); font-size: .94rem; }

.model-grid { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(310px, .85fr); gap: 25px; }
.content-panel { padding: 29px; border: 1px solid var(--ptv-line); border-radius: 19px; background: #fff; }
.content-panel h3 { margin: 0 0 14px; font-family: Georgia, "Times New Roman", serif; font-size: 1.5rem; font-weight: 500; }
.check-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px 18px; margin: 0; padding: 0; list-style: none; }
.check-list li { position: relative; padding-left: 25px; color: #435461; }
.check-list li::before { content: "✓"; position: absolute; left: 0; color: #087460; font-weight: 900; }
.metric-list { display: grid; gap: 10px; margin: 0; padding: 0; list-style: none; }
.metric-list li { display: flex; justify-content: space-between; gap: 20px; padding: 10px 0; border-bottom: 1px solid var(--ptv-line); }
.metric-list li:last-child { border-bottom: 0; }
.metric-list strong { color: var(--ptv-blue); }

.faq-list { display: grid; gap: 12px; max-width: 900px; }
.faq-list details { border: 1px solid var(--ptv-line); border-radius: 14px; background: #fff; }
.faq-list summary { cursor: pointer; padding: 18px 21px; font-weight: 800; }
.faq-list p { margin: 0; padding: 0 21px 20px; color: var(--ptv-muted); }

.course-cta { padding: 42px; border-radius: 23px; color: #fff; background: linear-gradient(125deg, var(--ptv-navy-deep), var(--ptv-navy)); box-shadow: var(--ptv-shadow); }
.course-cta h2 { margin: 0 0 10px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(1.9rem, 3.5vw, 3rem); font-weight: 500; }
.course-cta p { max-width: 760px; margin: 0 0 23px; color: #c9d8df; }
.resource-links { display: flex; flex-wrap: wrap; gap: 12px; }
.disclaimer { margin: 18px 0 0; color: #91a7b4; font-size: .8rem; }

.site-footer { padding: 38px 0; background: #071620; color: #a9bbc6; }
.footer-grid { display: grid; grid-template-columns: 1.2fr 1fr 1fr; gap: 38px; }
.site-footer h2 { margin: 0 0 10px; color: #fff; font-size: 1rem; }
.site-footer p { margin: 0; max-width: 420px; }
.footer-links { display: grid; gap: 7px; }
.footer-links a { color: #c8d6dd; text-decoration: none; }
.footer-links a:hover { color: var(--ptv-cyan); }

@media (max-width: 940px) {
  .hero-grid, .model-grid { grid-template-columns: 1fr; }
  .playlist-card { max-width: 720px; }
  .workflow-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .main-nav { display: none; }
  .nav-cta { margin-left: auto; }
}
@media (max-width: 680px) {
  .page-shell, .nav-shell { width: min(100% - 28px, 1180px); }
  .nav-shell { min-height: 60px; }
  .nav-cta { padding: 8px 12px; font-size: .84rem; }
  .hero { padding: 52px 0; }
  .hero-grid { gap: 38px; }
  .definition-grid, .video-grid, .workflow-grid, .footer-grid { grid-template-columns: 1fr; }
  .roadmap li { grid-template-columns: 54px minmax(0,1fr); gap: 14px; align-items: start; }
  .module-number { width: 48px; height: 48px; border-radius: 14px; }
  .roadmap .status { grid-column: 2; justify-self: start; }
  .check-list { grid-template-columns: 1fr; }
  .section { padding: 62px 0; }
  .course-cta { padding: 28px 23px; }
}