/* InteractLab — site design system */
@import url('https://fonts.googleapis.com/css2?family=DM+Sans:ital,opsz,wght@0,9..40,400;0,9..40,500;0,9..40,600;0,9..40,700&family=JetBrains+Mono:wght@400;500&display=swap');

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --font-sans: 'DM Sans', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;
  --bg: #fafaf9;
  --bg-elevated: #ffffff;
  --bg-muted: #f5f5f4;
  --bg-subtle: #eeede9;
  --text: #0f172a;
  --text-secondary: #64748b;
  --text-tertiary: #94a3b8;
  --border: rgba(15, 23, 42, 0.08);
  --border-strong: rgba(15, 23, 42, 0.14);
  --radius: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 20px 50px rgba(15, 23, 42, 0.08);
  --teal: #0d9488;
  --teal-dark: #0f766e;
  --teal-light: #ccfbf1;
  --teal-glow: rgba(13, 148, 136, 0.25);
  --purple: #7c3aed;
  --purple-light: #ede9fe;
  --amber: #d97706;
  --amber-light: #fef3c7;
  --blue: #2563eb;
  --blue-light: #dbeafe;
  --green: #059669;
  --green-light: #d1fae5;
  --header-h: 60px;
  --content-wide: 1120px;
  --content-narrow: 820px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0c0c0b;
    --bg-elevated: #1c1c1a;
    --bg-muted: #252523;
    --bg-subtle: #2e2e2b;
    --text: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-tertiary: #64748b;
    --border: rgba(255, 255, 255, 0.08);
    --border-strong: rgba(255, 255, 255, 0.14);
    --teal-light: #042f2e;
    --purple-light: #2e1065;
    --amber-light: #451a03;
    --blue-light: #1e3a8a;
    --green-light: #064e3b;
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.35);
    --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.45);
  }
}

html { scroll-behavior: smooth; }

body.site-body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.5;
  min-height: 100vh;
}

/* ─── Header ─── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 24px;
  background: color-mix(in srgb, var(--bg-elevated) 88%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-weight: 600;
  font-size: 17px;
  letter-spacing: -0.02em;
}

.logo-mark {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius);
  background: linear-gradient(135deg, var(--teal) 0%, var(--teal-dark) 100%);
  color: #fff;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 500;
  box-shadow: 0 4px 12px var(--teal-glow);
}

.logo-text span { color: var(--teal); }

.site-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.nav-link {
  padding: 8px 14px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: var(--radius);
  transition: color 0.15s, background 0.15s;
}

.nav-link:hover {
  color: var(--text);
  background: var(--bg-muted);
}

.nav-link.active {
  color: var(--teal-dark);
  background: var(--teal-light);
}

@media (prefers-color-scheme: dark) {
  .nav-link.active { color: #5eead4; }
}

.nav-toggle {
  display: none;
  padding: 8px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  background: var(--bg-elevated);
  cursor: pointer;
  color: var(--text);
}

@media (max-width: 640px) {
  .nav-toggle { display: block; }
  .site-nav {
    display: none;
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    flex-direction: column;
    padding: 12px;
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
  }
  .site-nav.open { display: flex; }
  .nav-link { width: 100%; text-align: left; }
}

/* ─── Footer ─── */
.site-footer {
  margin-top: auto;
  padding: 32px 24px;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 13px;
  color: var(--text-secondary);
}

.site-footer a {
  color: var(--teal);
  text-decoration: none;
}

.site-footer a:hover { text-decoration: underline; }

/* ─── Tutorial shell ─── */
.tutorial-shell {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.tutorial-hero {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: 28px 20px 8px;
  width: 100%;
}

.tutorial-hero .breadcrumb {
  font-size: 12px;
  color: var(--text-tertiary);
  margin-bottom: 12px;
  font-family: var(--font-mono);
}

.tutorial-hero .breadcrumb a {
  color: var(--text-secondary);
  text-decoration: none;
}

.tutorial-hero .breadcrumb a:hover { color: var(--teal); }

.tutorial-hero h1 {
  font-size: clamp(22px, 4vw, 28px);
  font-weight: 600;
  letter-spacing: -0.03em;
  margin-bottom: 8px;
  line-height: 1.2;
}

.tutorial-hero .hero-desc {
  font-size: 15px;
  color: var(--text-secondary);
  max-width: 52ch;
  line-height: 1.6;
}

.tutorial-hero .hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.hero-tag {
  font-size: 11px;
  font-weight: 500;
  font-family: var(--font-mono);
  padding: 4px 10px;
  border-radius: 20px;
  background: var(--bg-muted);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.tutorial-main {
  max-width: var(--content-narrow);
  margin: 0 auto;
  padding: 0 20px 48px;
  width: 100%;
}

.tutorial-main > h1,
.tutorial-main > .subtitle { display: none; }

/* ─── Home page ─── */
.home-wrap {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.home-hero {
  position: relative;
  overflow: hidden;
  padding: 56px 24px 72px;
  text-align: center;
}

.home-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 50% -20%, var(--teal-glow), transparent 55%),
    radial-gradient(ellipse 50% 40% at 90% 50%, rgba(124, 58, 237, 0.12), transparent 50%),
    radial-gradient(ellipse 40% 35% at 10% 80%, rgba(37, 99, 235, 0.1), transparent 45%);
  pointer-events: none;
}

.home-hero-inner {
  position: relative;
  max-width: 720px;
  margin: 0 auto;
}

.home-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  font-weight: 500;
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--teal-dark);
  background: var(--teal-light);
  padding: 6px 14px;
  border-radius: 20px;
  margin-bottom: 20px;
}

@media (prefers-color-scheme: dark) {
  .home-eyebrow { color: #5eead4; }
}

.home-hero h1 {
  font-size: clamp(32px, 6vw, 48px);
  font-weight: 700;
  letter-spacing: -0.04em;
  line-height: 1.1;
  margin-bottom: 16px;
}

.home-hero h1 em {
  font-style: normal;
  background: linear-gradient(135deg, var(--teal) 0%, var(--purple) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.home-lead {
  font-size: 18px;
  color: var(--text-secondary);
  line-height: 1.65;
  max-width: 540px;
  margin: 0 auto 28px;
}

.home-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  font-size: 14px;
  font-weight: 600;
  font-family: var(--font-sans);
  text-decoration: none;
  border-radius: var(--radius);
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s, box-shadow 0.15s, background 0.15s;
}

.btn:hover { transform: translateY(-1px); }

.btn-primary {
  background: var(--teal);
  color: #fff;
  box-shadow: 0 4px 14px var(--teal-glow);
}

.btn-primary:hover {
  background: var(--teal-dark);
  box-shadow: 0 6px 20px var(--teal-glow);
}

.btn-ghost {
  background: var(--bg-elevated);
  color: var(--text);
  border-color: var(--border-strong);
}

.btn-ghost:hover { background: var(--bg-muted); }

/* Sections */
.home-section {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: 0 24px 64px;
}

.section-head {
  margin-bottom: 28px;
}

.section-head h2 {
  font-size: 22px;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.section-head p {
  font-size: 15px;
  color: var(--text-secondary);
  max-width: 50ch;
}

/* Tutorial cards */
.tutorial-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}

.tutorial-card {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: inherit;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
  box-shadow: var(--shadow-sm);
}

.tutorial-card:hover {
  border-color: var(--teal);
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
  margin-bottom: 16px;
}

.card-icon.teal { background: var(--teal-light); }
.card-icon.purple { background: var(--purple-light); }
.card-icon.amber { background: var(--amber-light); }

.tutorial-card h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.02em;
}

.tutorial-card p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
  flex: 1;
}

.card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.card-meta span {
  font-size: 11px;
  font-family: var(--font-mono);
  color: var(--text-tertiary);
  padding: 3px 8px;
  background: var(--bg-muted);
  border-radius: 4px;
}

.card-arrow {
  margin-top: 16px;
  font-size: 13px;
  font-weight: 600;
  color: var(--teal);
}

/* Learning path */
.path-steps {
  display: grid;
  gap: 12px;
}

.path-step {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  padding: 18px 20px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
}

.path-num {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  background: var(--teal);
  color: #fff;
  border-radius: 50%;
}

.path-step h4 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 4px;
}

.path-step p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.55;
}

.path-step a {
  font-size: 13px;
  font-weight: 600;
  color: var(--teal);
  text-decoration: none;
  margin-top: 6px;
  display: inline-block;
}

.path-step a:hover { text-decoration: underline; }

/* How it works */
.features-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.feature-box {
  padding: 20px;
  border-radius: var(--radius-lg);
  background: var(--bg-muted);
  border: 1px solid var(--border);
}

.feature-box h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
}

.feature-box p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.55;
}