:root {
  color-scheme: light;
  --ink: #15171a;
  --muted: #5c6670;
  --line: #d9e3ea;
  --paper: #ffffff;
  --soft: #f5f9fb;
  --blue: #0877df;
  --teal: #08aeb5;
  --orange: #f47b20;
  --shadow: 0 18px 50px rgba(15, 35, 52, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--ink);
  font-family:
    Aptos,
    "Segoe UI",
    system-ui,
    -apple-system,
    sans-serif;
  background:
    linear-gradient(135deg, rgba(8, 174, 181, 0.08), transparent 38%),
    linear-gradient(315deg, rgba(244, 123, 32, 0.08), transparent 35%),
    var(--paper);
}

a {
  color: #075da9;
  font-weight: 700;
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.18em;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem clamp(1rem, 3vw, 2.5rem);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--ink);
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 2.9rem;
  height: 2.9rem;
  place-items: center;
  border: 3px solid var(--ink);
  border-radius: 0.7rem;
  color: var(--blue);
  font-weight: 900;
  box-shadow: 0.25rem 0.25rem 0 var(--teal);
}

.brand small {
  display: block;
  color: var(--muted);
  font-weight: 700;
}

nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 0.35rem;
}

nav a {
  padding: 0.55rem 0.75rem;
  border-radius: 999px;
  color: var(--ink);
  text-decoration: none;
}

nav a[aria-current="page"],
nav a:hover {
  background: #e7f8fb;
  color: #064f78;
}

main {
  width: min(1160px, calc(100% - 2rem));
  margin: 0 auto;
}

.hero-grid,
.lesson-hero {
  display: grid;
  grid-template-columns: minmax(0, 0.82fr) minmax(300px, 1fr);
  gap: clamp(1.25rem, 4vw, 3rem);
  align-items: center;
  padding: clamp(1.4rem, 4vw, 3rem) 0;
}

.hero-copy h1,
.lesson-hero h1,
.page-shell h1 {
  max-width: 12ch;
  margin: 0;
  font-size: clamp(2.4rem, 7vw, 5.5rem);
  line-height: 0.94;
  letter-spacing: 0;
}

.hero-copy p,
.lesson-hero p,
.lede {
  max-width: 66ch;
  color: var(--muted);
  font-size: 1.1rem;
  line-height: 1.6;
}

.eyebrow {
  margin: 0 0 0.5rem;
  color: #087178;
  font-size: 0.84rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.hero-art,
.lesson-hero img {
  display: block;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 1rem;
  box-shadow: var(--shadow);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.3rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.8rem;
  padding: 0.75rem 1rem;
  border: 2px solid var(--ink);
  border-radius: 0.8rem;
  text-decoration: none;
}

.button.primary {
  color: white;
  background: var(--ink);
}

.button.secondary {
  color: var(--ink);
  background: white;
}

.section-heading,
.page-shell {
  padding: 2rem 0 1rem;
}

.section-heading h2,
.page-shell h1,
.page-shell h2,
.panel h2 {
  margin: 0 0 0.75rem;
}

.lesson-grid,
.content-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.lesson-card,
.panel {
  display: flex;
  gap: 1rem;
  min-height: 13rem;
  padding: 1.1rem;
  background: rgba(255, 255, 255, 0.88);
  border: 1px solid var(--line);
  border-radius: 1rem;
  box-shadow: 0 10px 30px rgba(15, 35, 52, 0.06);
}

.panel {
  display: block;
}

.lesson-card.is-ready {
  border-color: rgba(8, 174, 181, 0.45);
  box-shadow: var(--shadow);
}

.lesson-number {
  flex: 0 0 auto;
  display: grid;
  width: 3.4rem;
  height: 3.4rem;
  place-items: center;
  border: 3px solid var(--ink);
  border-radius: 0.8rem;
  color: var(--orange);
  font-size: 1.25rem;
  font-weight: 900;
}

.status {
  margin: 0;
  color: var(--teal);
  font-size: 0.8rem;
  font-weight: 900;
  text-transform: uppercase;
}

.lesson-card h3 {
  margin: 0.2rem 0 0.4rem;
  font-size: 1.4rem;
}

.lesson-card p,
.panel p,
.check-list {
  color: var(--muted);
  line-height: 1.55;
}

.video-panel {
  background:
    linear-gradient(135deg, rgba(8, 119, 223, 0.12), transparent),
    #ffffff;
  border-style: dashed;
}

.narrow {
  max-width: 820px;
}

pre {
  overflow-x: auto;
  padding: 1rem;
  color: #eef8ff;
  background: #17202a;
  border-radius: 0.8rem;
  font-size: 0.95rem;
  line-height: 1.5;
}

.check-list {
  padding-left: 1.25rem;
}

.check-list li {
  margin-bottom: 0.45rem;
}

.download-section {
  padding: 1rem 0;
}

.download-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem;
}

.download-list.compact {
  grid-template-columns: 1fr;
}

.download-list a {
  display: block;
  padding: 0.85rem 0.95rem;
  color: var(--ink);
  background: white;
  border: 1px solid var(--line);
  border-radius: 0.75rem;
  text-decoration: none;
}

.download-list a span {
  display: block;
  margin-top: 0.28rem;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 500;
  line-height: 1.4;
}

.download-list a:hover {
  border-color: var(--teal);
  box-shadow: 0 8px 24px rgba(8, 174, 181, 0.12);
}

.lesson-nav {
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0 2rem;
  color: var(--muted);
}

.site-footer {
  margin-top: 3rem;
  padding: 1.4rem clamp(1rem, 3vw, 2.5rem);
  color: var(--muted);
  border-top: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.78);
}

.teacher-start,
.editable-note {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  margin: 2rem 0;
  padding: 1.25rem;
  background: rgba(231, 248, 251, 0.72);
  border: 1px solid rgba(8, 174, 181, 0.35);
  border-radius: 1rem;
}

.teacher-start h2,
.editable-note h2 {
  margin: 0 0 0.45rem;
}

.teacher-start p,
.editable-note p,
.transcript-link {
  color: var(--muted);
  line-height: 1.5;
}

a:focus-visible,
button:focus-visible,
video:focus-visible {
  outline: 3px solid var(--orange);
  outline-offset: 3px;
}

@media (max-width: 780px) {
  .site-header,
  .brand {
    align-items: flex-start;
  }

  .site-header {
    position: static;
    flex-direction: column;
  }

  nav {
    justify-content: flex-start;
  }

  .hero-grid,
  .lesson-hero,
  .lesson-grid,
  .content-grid,
  .download-list {
    grid-template-columns: 1fr;
  }

  .teacher-start,
  .editable-note {
    align-items: flex-start;
    flex-direction: column;
  }

  .hero-copy h1,
  .lesson-hero h1,
  .page-shell h1 {
    font-size: clamp(2.25rem, 14vw, 3.4rem);
  }
}


.lesson-video {
  display: block;
  width: 100%;
  margin-top: 1rem;
  border: 1px solid var(--line);
  border-radius: 0.8rem;
  background: #111820;
}