:root {
  --bg: #0a1530;
  --bg-elev: #111e44;
  --ink: #f4f6ff;
  --ink-dim: #aab3d4;
  --accent: #6366f1;
  --accent-hot: #818cf8;
  --rule: rgba(255, 255, 255, 0.08);
  --max-w: 920px;
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent-hot); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Header / wordmark */
.site-header {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 28px 24px 0;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.01em;
}
.wordmark:hover { text-decoration: none; }
.wordmark .mark { width: 28px; height: 28px; display: block; border-radius: 6px; }
.wordmark .dot { color: var(--accent); }

/* Main layout */
main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 24px;
}

section { margin: 56px 0; }
section:first-child { margin-top: 32px; }

h1, h2, h3 { letter-spacing: -0.02em; line-height: 1.15; }

/* Hero */
.hero h1 {
  font-size: clamp(28px, 5vw, 44px);
  font-weight: 700;
  margin: 0 0 16px;
}
.hero h1 em {
  font-style: normal;
  color: var(--accent-hot);
}
.lede {
  font-size: clamp(16px, 2vw, 19px);
  color: var(--ink-dim);
  max-width: 60ch;
  margin: 0 0 28px;
}

.cta-row { display: flex; gap: 12px; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 10px 18px;
  border-radius: 8px;
  border: 1px solid var(--rule);
  background: transparent;
  color: var(--ink);
  font-weight: 600;
  font-size: 15px;
}
.btn:hover {
  text-decoration: none;
  border-color: var(--accent);
  background: rgba(99, 102, 241, 0.1);
}
.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
}
.btn.primary:hover {
  background: var(--accent-hot);
  border-color: var(--accent-hot);
}

/* Lessons */
.lessons h2,
.channels h2 {
  font-size: 22px;
  margin: 0 0 8px;
}
.section-lede {
  color: var(--ink-dim);
  margin: 0 0 20px;
  max-width: 65ch;
}

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

.lesson-list a {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 20px;
  padding: 18px 20px;
  background: var(--bg-elev);
  border: 1px solid var(--rule);
  border-radius: 10px;
  color: var(--ink);
}
.lesson-list a:hover {
  text-decoration: none;
  border-color: var(--accent);
  transform: translateY(-1px);
  transition: all 0.15s ease;
}

.lesson-num {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 13px;
  color: var(--accent-hot);
  font-weight: 600;
}
.lesson-body { display: grid; gap: 4px; }
.lesson-body strong { font-size: 17px; font-weight: 600; }
.lesson-blurb { color: var(--ink-dim); font-size: 14px; }
.arrow { color: var(--ink-dim); font-size: 20px; }
.lesson-list a:hover .arrow { color: var(--accent-hot); }

/* Channels */
.channel-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
}
.channel-grid a {
  display: block;
  padding: 16px 18px;
  background: var(--bg-elev);
  border: 1px solid var(--rule);
  border-radius: 10px;
  color: var(--ink);
}
.channel-grid a:hover {
  text-decoration: none;
  border-color: var(--accent);
}
.channel-grid strong { display: block; font-size: 15px; margin-bottom: 2px; }
.channel-grid span { font-size: 13px; color: var(--ink-dim); }

/* Footer */
footer {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 32px 24px 56px;
  border-top: 1px solid var(--rule);
  color: var(--ink-dim);
  font-size: 13px;
}
footer p { margin: 16px 0 0; }