:root {
  --site-ink: #17212c;
  --site-muted: #5c6875;
  --site-bg: #f5f2ec;
  --site-paper: #ffffff;
  --site-line: #d8d4ca;
  --site-teal: #177f82;
  --site-green: #2c7a58;
  --site-amber: #b76f1f;
  --site-rose: #a84949;
  --site-blue: #315f97;
  --site-radius: 8px;
  --site-shadow: 0 18px 48px rgba(23, 33, 44, 0.12);
  --site-font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
}

.site-skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 200;
  padding: 10px 12px;
  border-radius: var(--site-radius);
  background: var(--site-ink);
  color: #fff;
  transform: translateY(-140%);
}

.site-skip-link:focus {
  transform: translateY(0);
}

.site-coursebar {
  position: relative;
  z-index: 80;
  min-height: 48px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 8px max(18px, calc((100% - 1480px) / 2));
  border-bottom: 1px solid rgba(216, 212, 202, 0.9);
  background: #fffaf2;
  color: var(--site-ink);
  font-family: var(--site-font);
  font-size: 14px;
  line-height: 1.4;
}

.site-coursebar a {
  color: inherit;
  text-decoration: none;
}

.site-coursebar a:hover {
  color: var(--site-teal);
}

.site-coursebar-brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 800;
  white-space: nowrap;
}

.site-coursebar-mark {
  width: 28px;
  height: 28px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(23, 127, 130, 0.34);
  border-radius: 7px;
  background: #fff;
  color: var(--site-teal);
  font-size: 12px;
}

.site-coursebar-links {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  color: var(--site-muted);
}

.site-coursebar-links a {
  white-space: nowrap;
}

body.home-page {
  margin: 0;
  color: var(--site-ink);
  background: var(--site-bg);
  font-family: var(--site-font);
  line-height: 1.65;
}

.home-page * {
  box-sizing: border-box;
}

.home-page a {
  color: inherit;
  text-decoration: none;
}

.home-page a:focus-visible,
.home-page button:focus-visible,
.home-page input:focus-visible,
.site-coursebar a:focus-visible {
  outline: 3px solid rgba(23, 127, 130, 0.34);
  outline-offset: 3px;
}

.site-shell {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
}

.home-nav {
  position: sticky;
  top: 0;
  z-index: 90;
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 0 max(20px, calc((100% - 1180px) / 2));
  border-bottom: 1px solid rgba(255, 255, 255, 0.16);
  background: rgba(23, 33, 44, 0.8);
  color: #fff;
  backdrop-filter: blur(14px);
}

.home-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  font-weight: 850;
}

.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border: 1px solid rgba(255, 255, 255, 0.42);
  border-radius: var(--site-radius);
  background: rgba(255, 255, 255, 0.13);
}

.home-nav-links {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 16px;
  color: rgba(255, 255, 255, 0.78);
  font-size: 14px;
}

.home-nav-links a {
  white-space: nowrap;
}

.home-nav-links a:hover {
  color: #fff;
}

.home-hero {
  position: relative;
  min-height: 82vh;
  margin-top: -72px;
  padding: 160px 0 96px;
  display: flex;
  align-items: center;
  color: #fff;
  background:
    linear-gradient(90deg, rgba(12, 19, 27, 0.88), rgba(12, 19, 27, 0.58) 48%, rgba(12, 19, 27, 0.24)),
    url("assets/ai-course-hero.png") center / cover no-repeat;
}

.hero-content {
  max-width: 1180px;
}

.hero-kicker,
.section-kicker {
  margin: 0 0 12px;
  color: var(--site-amber);
  font-size: 14px;
  font-weight: 850;
  letter-spacing: 0;
}

.hero-kicker {
  color: #f2b15e;
}

.home-hero h1 {
  max-width: 780px;
  margin: 0;
  font-size: 58px;
  line-height: 1.08;
  letter-spacing: 0;
}

.hero-lead {
  max-width: 720px;
  margin: 24px 0 0;
  color: rgba(255, 255, 255, 0.84);
  font-size: 20px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}

.primary-action,
.secondary-action {
  min-height: 46px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 18px;
  border-radius: var(--site-radius);
  font-weight: 800;
}

.primary-action {
  background: #f2b15e;
  color: #1d242c;
}

.secondary-action {
  border: 1px solid rgba(255, 255, 255, 0.34);
  color: #fff;
}

.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin: 40px 0 0;
  padding: 0;
}

.hero-stats div {
  min-width: 118px;
  padding: 14px 16px;
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--site-radius);
  background: rgba(255, 255, 255, 0.09);
}

.hero-stats dt {
  font-size: 28px;
  line-height: 1;
  font-weight: 900;
}

.hero-stats dd {
  margin: 6px 0 0;
  color: rgba(255, 255, 255, 0.74);
  font-size: 13px;
}

.site-band {
  padding: 76px 0;
}

.intro-band,
.answer-band {
  background: #fff;
}

.search-band {
  border-top: 1px solid var(--site-line);
  border-bottom: 1px solid var(--site-line);
  background: #eee9df;
}

.section-head {
  max-width: 760px;
}

.section-head h2 {
  margin: 0;
  font-size: 36px;
  line-height: 1.18;
  letter-spacing: 0;
}

.section-head p {
  margin: 16px 0 0;
  color: var(--site-muted);
  font-size: 17px;
}

.intro-layout,
.answer-layout,
.faq-layout {
  display: grid;
  grid-template-columns: minmax(0, 0.88fr) minmax(320px, 1fr);
  gap: 56px;
  align-items: start;
}

.path-list {
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
  list-style: none;
}

.path-list li {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  align-items: center;
  gap: 16px;
  padding: 18px;
  border: 1px solid var(--site-line);
  border-radius: var(--site-radius);
  background: #fbfaf6;
}

.path-list span {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: var(--site-radius);
  background: #1d2f35;
  color: #fff;
  font-weight: 900;
}

.path-list strong {
  font-size: 18px;
  overflow-wrap: anywhere;
}

.course-tools {
  margin-top: 28px;
  display: grid;
  gap: 16px;
}

.search-box {
  display: grid;
  gap: 8px;
  max-width: 520px;
  font-weight: 800;
}

.search-box input {
  width: 100%;
  min-height: 48px;
  border: 1px solid var(--site-line);
  border-radius: var(--site-radius);
  padding: 0 14px;
  background: #fff;
  color: var(--site-ink);
  font: inherit;
}

.filter-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.site-filter {
  min-height: 40px;
  border: 1px solid var(--site-line);
  border-radius: var(--site-radius);
  padding: 8px 12px;
  background: #fff;
  color: var(--site-ink);
  font: inherit;
  font-weight: 750;
  cursor: pointer;
}

.site-filter.is-active {
  border-color: rgba(23, 127, 130, 0.35);
  background: #dff0ed;
  color: #0f595c;
}

.result-count {
  margin: 0;
  color: var(--site-muted);
  font-weight: 750;
}

.course-section {
  background: var(--site-bg);
}

.course-section:nth-of-type(2n) {
  background: #f8f7f2;
}

.course-grid {
  margin-top: 30px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.course-card {
  min-height: 252px;
  border: 1px solid var(--site-line);
  border-radius: var(--site-radius);
  background: var(--site-paper);
  box-shadow: 0 10px 26px rgba(23, 33, 44, 0.06);
  transition: transform 160ms ease, border-color 160ms ease, box-shadow 160ms ease;
}

.course-card:hover {
  transform: translateY(-3px);
  border-color: rgba(23, 127, 130, 0.36);
  box-shadow: var(--site-shadow);
}

.course-card.is-hidden {
  display: none;
}

.course-card-link {
  min-height: 252px;
  display: flex;
  flex-direction: column;
  padding: 20px;
}

.course-index {
  color: var(--site-amber);
  font-weight: 900;
  font-size: 13px;
}

.course-meta {
  margin-top: 12px;
  color: var(--site-muted);
  font-size: 13px;
  font-weight: 750;
}

.course-card h3 {
  margin: 12px 0 0;
  font-size: 21px;
  line-height: 1.3;
  letter-spacing: 0;
  overflow-wrap: anywhere;
}

.course-card p {
  margin: 12px 0 0;
  color: var(--site-muted);
  font-size: 15px;
}

.course-open {
  margin-top: auto;
  padding-top: 20px;
  color: var(--site-teal);
  font-weight: 850;
}

.answer-points {
  display: grid;
  gap: 14px;
}

.answer-points p {
  margin: 0;
  padding: 18px;
  border-left: 4px solid var(--site-teal);
  border-radius: var(--site-radius);
  background: #eef8f5;
}

.faq-list {
  display: grid;
  gap: 12px;
}

.faq-list details {
  border: 1px solid var(--site-line);
  border-radius: var(--site-radius);
  background: #fff;
}

.faq-list summary {
  cursor: pointer;
  padding: 18px;
  font-weight: 850;
}

.faq-list p {
  margin: 0;
  padding: 0 18px 18px;
  color: var(--site-muted);
}

.home-footer {
  padding: 34px 0;
  border-top: 1px solid var(--site-line);
  background: #17212c;
  color: rgba(255, 255, 255, 0.82);
}

.footer-layout {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.footer-layout p {
  margin: 0;
}

.footer-layout nav {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.footer-layout a:hover {
  color: #fff;
}

@media (max-width: 980px) {
  .home-nav {
    align-items: flex-start;
    flex-direction: column;
    padding-top: 14px;
    padding-bottom: 14px;
  }

  .home-nav-links {
    justify-content: flex-start;
    overflow-x: auto;
    width: 100%;
    padding-bottom: 4px;
  }

  .home-hero {
    margin-top: -116px;
    padding-top: 180px;
  }

  .home-hero h1 {
    font-size: 44px;
  }

  .intro-layout,
  .answer-layout,
  .faq-layout {
    grid-template-columns: 1fr;
  }

  .course-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 680px) {
  .site-shell {
    width: min(100% - 28px, 1180px);
  }

  .site-coursebar {
    align-items: flex-start;
    flex-direction: column;
  }

  .home-hero {
    min-height: 78vh;
    padding-bottom: 72px;
  }

  .home-hero h1 {
    font-size: 34px;
  }

  .hero-lead {
    font-size: 17px;
  }

  .section-head h2 {
    font-size: 29px;
  }

  .site-band {
    padding: 54px 0;
  }

  .course-grid {
    grid-template-columns: 1fr;
  }

  .footer-layout {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  .course-card {
    transition: none;
  }

  .course-card:hover {
    transform: none;
  }
}