/* try-ai-tutor — light landing theme */

:root {
  --fg: #1c1c1f;
  --fg-muted: #5a5a63;
  --bg: #fcfcfd;
  --bg-alt: #f2f4f8;
  --accent: #2a6fb3;
  --accent-hover: #1f5285;
  --border: #e3e5ea;
  --code-bg: #eef0f4;
  --max-width: 780px;
  --wide-width: 1080px;
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, Menlo, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  background: var(--code-bg);
  padding: 0.12em 0.38em;
  border-radius: 4px;
}

h1, h2, h3 {
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.25;
}
h1 { font-size: 2.2rem; margin: 0 0 0.6em; }
h2 { font-size: 1.55rem; margin: 0 0 0.5em; }
h3 { font-size: 1.15rem; margin: 1.6em 0 0.4em; }

.container {
  max-width: var(--wide-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.prose {
  max-width: var(--max-width);
}
.prose p, .prose ul, .prose ol { margin: 0.8em 0; }
.prose ul, .prose ol { padding-left: 1.5em; }
.prose li { margin: 0.3em 0; }

/* ---- Header ---- */
.site-header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem 1.25rem;
  gap: 1rem;
}
.brand {
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--fg);
  text-decoration: none;
  white-space: nowrap;
}
.brand-mark { color: var(--accent); }
.brand-dot { color: var(--fg-muted); margin: 0 0.05em; }
.brand:hover { text-decoration: none; }

.site-nav {
  display: flex;
  gap: 1.2rem;
  flex-wrap: wrap;
  justify-content: flex-end;
}
.site-nav a {
  color: var(--fg-muted);
  font-size: 0.94rem;
  font-weight: 500;
}
.site-nav a:hover { color: var(--accent); text-decoration: none; }

/* ---- Hero ---- */
.hero {
  padding: 4.5rem 0 3rem;
  border-bottom: 1px solid var(--border);
  text-align: center;
}
.hero h1 {
  font-size: 3rem;
  margin-bottom: 0.3em;
}
.hero-tagline {
  font-size: 1.2rem;
  color: var(--fg-muted);
  max-width: 640px;
  margin: 0 auto 1.8em;
}
.hero-actions {
  display: flex;
  gap: 0.8rem;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-block;
  padding: 0.62em 1.4em;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.98rem;
  border: 1px solid transparent;
  transition: background 0.15s, border-color 0.15s;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover {
  background: var(--accent-hover);
  color: #fff;
  text-decoration: none;
}
.btn-secondary {
  background: transparent;
  color: var(--accent);
  border-color: var(--border);
}
.btn-secondary:hover {
  border-color: var(--accent);
  text-decoration: none;
}

/* ---- Sections ---- */
.section {
  padding: 3rem 0;
}
.section--alt {
  background: var(--bg-alt);
}
.section .prose {
  margin-left: auto;
  margin-right: auto;
}

/* ---- Architecture row ---- */
.arch {
  display: flex;
  align-items: stretch;
  justify-content: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin: 1.5rem 0;
}
.arch-box {
  flex: 1 1 180px;
  min-width: 160px;
  max-width: 220px;
  padding: 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  text-align: center;
  font-size: 0.95rem;
  line-height: 1.4;
}
.arch-box span {
  display: block;
  font-size: 0.8rem;
  color: var(--fg-muted);
  margin: 0.3em 0 0.5em;
  font-family: var(--font-mono);
}
.arch-arrow {
  display: flex;
  align-items: center;
  color: var(--fg-muted);
  font-size: 1.5rem;
  padding: 0 0.2rem;
}

/* ---- Video embeds ---- */
.video-wrap {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  overflow: hidden;
  max-width: 100%;
  margin: 1.2rem 0 2rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #000;
}
.video-wrap iframe {
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  border: 0;
}

/* ---- Misc ---- */
.note {
  color: var(--fg-muted);
  font-size: 0.92rem;
  font-style: italic;
}
.lede {
  color: var(--fg-muted);
  font-size: 1.1rem;
}

/* ---- Footer ---- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  color: var(--fg-muted);
  font-size: 0.9rem;
  text-align: center;
}
.footer-inner p { margin: 0.3em 0; }
.build {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  opacity: 0.7;
}

/* ---- Responsive ---- */
@media (max-width: 640px) {
  .hero { padding: 3rem 0 2.2rem; }
  .hero h1 { font-size: 2.2rem; }
  .hero-tagline { font-size: 1.05rem; }
  .section { padding: 2.2rem 0; }
  .arch-arrow { transform: rotate(90deg); }
  .site-nav { font-size: 0.88rem; gap: 0.8rem; }
}