/* TurboVec Tutorial — ML/AI tutorial theme */
:root {
  --bg: #080c14;
  --surface: #111827;
  --surface2: #1a2236;
  --border: #253050;
  --text: #e2e5ed;
  --text2: #9098b0;
  --accent: #6366f1;
  --accent-dim: #4f46e5;
  --warn: #f59e0b;
  --code-bg: #0a0e1a;
  --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --mono: 'Cascadia Code', 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

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

html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
}

/* Nav */
nav {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(12px);
}
.nav-inner {
  max-width: 900px; margin: 0 auto; padding: 0 24px;
  display: flex; align-items: center; justify-content: space-between; height: 56px;
}
.nav-logo a {
  font-family: var(--mono); font-size: 1rem; font-weight: 600;
  color: var(--accent); text-decoration: none;
}
.nav-links { list-style: none; display: flex; gap: 24px; }
.nav-links a { color: var(--text2); text-decoration: none; font-size: 0.875rem; transition: color .15s; }
.nav-links a:hover { color: var(--text); }

/* Hero */
.hero {
  text-align: center; padding: 80px 24px 64px;
  max-width: 780px; margin: 0 auto;
}
.hero-badge {
  display: inline-block; background: var(--surface2); border: 1px solid var(--border);
  color: var(--accent); font-size: 0.75rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: 0.08em; padding: 4px 14px; border-radius: 100px; margin-bottom: 24px;
}
.hero h1 {
  font-size: 2.5rem; font-weight: 800; line-height: 1.2; letter-spacing: -0.02em;
  margin-bottom: 16px; color: #fff;
}
.hero .subtitle { font-size: 1.15rem; color: var(--text2); margin-bottom: 24px; line-height: 1.65; }
.hero-meta {
  display: flex; gap: 12px; justify-content: center; align-items: center;
  color: var(--text2); font-size: 0.9rem;
}

/* Sections */
.section {
  max-width: 800px; margin: 0 auto; padding: 64px 24px;
  border-top: 1px solid var(--border);
}
.section:first-of-type { border-top: none; }
.section .intro {
  color: var(--text2); font-size: 1.05rem; margin-bottom: 32px;
}

h2 {
  font-size: 1.75rem; font-weight: 700; margin-bottom: 24px;
  letter-spacing: -0.01em; color: #fff;
}
h3 { font-size: 1.2rem; font-weight: 600; margin: 28px 0 8px; color: #f0f0f5; }
h4 { font-size: 1rem; font-weight: 600; margin-bottom: 6px; color: #f0f0f5; }
p { margin-bottom: 14px; color: var(--text2); }
p strong { color: var(--text); }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
ul { margin: 0 0 14px 20px; color: var(--text2); }
li { margin-bottom: 6px; }
li strong { color: var(--text); }

/* Reason blocks */
.reason {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 24px; margin-bottom: 20px;
}
.reason h3 { margin-top: 0; }
.reason p { margin-bottom: 8px; }
.reason-why {
  font-size: 0.85rem; color: var(--accent); font-style: italic;
  border-left: 3px solid var(--accent-dim); padding-left: 12px;
}

/* Steps */
.step { margin-bottom: 36px; }
.step h3 { color: var(--accent); }

/* Code blocks */
.code-block {
  background: var(--code-bg); border: 1px solid var(--border);
  border-radius: 8px; padding: 16px 20px; margin: 12px 0 18px;
  font-family: var(--mono); font-size: 0.85rem; line-height: 1.65;
  overflow-x: auto; white-space: pre-wrap; word-break: break-word;
  color: #c9d1d9;
}
.cm { color: #8b949e; }
.st { color: #a5d6ff; }
.kw { color: #ff7b72; }
.kn { color: #ff7b72; }
.nn { color: #ffa657; }
.fn { color: #d2a8ff; }
code {
  background: var(--surface2); padding: 2px 6px; border-radius: 4px;
  font-family: var(--mono); font-size: 0.875em; color: var(--accent);
}
.code-block code { background: none; padding: 0; color: inherit; }

/* Callouts */
.callout {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 18px 22px; margin: 20px 0;
  font-size: 0.95rem;
}
.callout strong { color: var(--accent); }
.callout.warn { border-left: 3px solid var(--warn); }
.callout.warn strong { color: var(--warn); }
.callout.note { border-left: 3px solid var(--text2); }

/* Features grid */
.features-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 20px;
}
.feature-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 22px;
}
.feature-card h4 { color: var(--accent); }
.feature-card p { font-size: 0.95rem; margin-bottom: 0; }

/* Use cases */
.use-case {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 22px; margin-bottom: 16px;
}
.use-case h3 { margin-top: 0; }
.use-case p { margin-bottom: 0; }

/* FAQ */
.faq-item { margin-bottom: 2px; }
.faq-q {
  width: 100%; text-align: left; background: var(--surface);
  border: 1px solid var(--border); border-radius: 8px;
  padding: 16px 48px 16px 20px; font-size: 1rem; font-weight: 500;
  color: var(--text); cursor: pointer; position: relative;
  font-family: var(--font); transition: background .15s;
}
.faq-q:hover { background: var(--surface2); }
.faq-q::after {
  content: '+'; position: absolute; right: 20px; top: 50%;
  transform: translateY(-50%); font-size: 1.3rem; color: var(--accent);
  transition: transform .2s;
}
.faq-q.open::after { transform: translateY(-50%) rotate(45deg); }
.faq-q.open { background: var(--surface2); border-color: var(--accent-dim); }
.faq-a {
  display: none; background: var(--surface);
  border: 1px solid var(--border); border-top: none;
  border-radius: 0 0 8px 8px; padding: 0 20px 18px;
}
.faq-a.open { display: block; }
.faq-a p { font-size: 0.95rem; }

/* Next steps */
.next-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px; margin-top: 8px;
}
.next-card {
  display: flex; flex-direction: column; gap: 4px;
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 22px; text-decoration: none;
  transition: border-color .15s;
}
.next-card:hover { border-color: var(--accent-dim); text-decoration: none; }
.next-card .next-arrow { color: var(--accent); font-size: 1.1rem; font-weight: 700; }
.next-card strong { color: var(--text); font-size: 1rem; }
.next-card span { color: var(--text2); font-size: 0.875rem; }

/* Footer */
footer {
  text-align: center; padding: 48px 24px;
  border-top: 1px solid var(--border); color: var(--text2); font-size: 0.875rem;
}
footer a { color: var(--accent); }

/* Responsive */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.65rem; }
  .hero .subtitle { font-size: 1rem; }
  .section { padding: 48px 16px; }
  h2 { font-size: 1.4rem; }
  .features-grid { grid-template-columns: 1fr; }
  .next-grid { grid-template-columns: 1fr; }
  .nav-links { display: none; }
}