/* Explainer Site — Warm Light Theme
   Inter body, Playfair Display headings, responsive single-page layout. */

:root {
  --bg: #ffffff; --bg-alt: #f7f5f2; --bg-warm: #faf8f5; --bg-hero: #1b1f2e;
  --ink: #1a1a2e; --ink-2: #3d3d56; --ink-muted: #6b6b80;
  --ink-faint: #9c9cb0; --ink-on-dark: #f0eee8;
  --accent: #3b4cc0; --accent-hover: #2d3da6;
  --accent-light: #e8ebf8; --accent-bg: rgba(59,76,192,0.06);
  --warm-100: #fdf6ee; --warm-200: #f5ead8; --warm-300: #e8d5b8;
  --card-bg: #ffffff; --card-border: #e8e4de;
  --card-shadow: 0 1px 3px rgba(0,0,0,0.04), 0 4px 12px rgba(0,0,0,0.06);
  --card-shadow-lg: 0 4px 8px rgba(0,0,0,0.04), 0 12px 32px rgba(0,0,0,0.08);
  --code-bg: #f5f3ef; --code-border: #e2ddd5; --code-text: #2d2d44;
  --radius: 8px; --radius-lg: 12px; --max-w: 1120px; --nav-h: 64px;
  --font-body: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-display: "Playfair Display", Georgia, "Times New Roman", serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Cascadia Code", monospace;
  --sp-1: 0.25rem; --sp-2: 0.5rem; --sp-3: 0.75rem; --sp-4: 1rem;
  --sp-6: 1.5rem; --sp-8: 2rem; --sp-12: 3rem;
  --sp-16: 4rem; --sp-20: 5rem; --sp-24: 6rem;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-h) + var(--sp-4)); }
body {
  font-family: var(--font-body); font-size: 1rem; line-height: 1.7;
  color: var(--ink); background: var(--bg);
  -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--accent); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-hover); }

.wrap { max-width: var(--max-w); margin: 0 auto; padding: 0 var(--sp-6); }
@media (min-width: 768px) { .wrap { padding: 0 var(--sp-8); } }

h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 700; line-height: 1.2; color: var(--ink); }
h1 { font-size: clamp(2.25rem, 5vw, 3.5rem); letter-spacing: -0.02em; }
h2 { font-size: clamp(1.75rem, 3.5vw, 2.5rem); letter-spacing: -0.01em; margin-bottom: var(--sp-4); }
h3 { font-size: clamp(1.25rem, 2.5vw, 1.5rem); font-weight: 600; margin-bottom: var(--sp-3); }
p { margin-bottom: var(--sp-4); }
.tagline { font-size: clamp(1.125rem, 2vw, 1.375rem); line-height: 1.6; max-width: 640px; }

/* Navigation */
.site-nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--nav-h); background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--card-border); transition: box-shadow 0.3s;
}
.site-nav.scrolled { box-shadow: 0 1px 8px rgba(0,0,0,0.06); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 100%; }
.nav-brand { font-family: var(--font-display); font-size: 1.25rem; font-weight: 700; color: var(--ink); }
.nav-brand:hover { color: var(--accent); }
.nav-links { display: flex; gap: var(--sp-6); align-items: center; }
.nav-links a {
  font-size: 0.875rem; font-weight: 500; color: var(--ink-2);
  padding: var(--sp-2) 0; border-bottom: 2px solid transparent;
  transition: color 0.2s, border-color 0.2s;
}
.nav-links a:hover, .nav-links a.active { color: var(--accent); border-bottom-color: var(--accent); }
.nav-toggle {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: none; cursor: pointer; padding: var(--sp-2);
}
.nav-toggle span { display: block; width: 22px; height: 2px; background: var(--ink); border-radius: 2px; transition: transform 0.3s, opacity 0.3s; }

@media (max-width: 767px) {
  .nav-toggle { display: flex; }
  .nav-links {
    position: fixed; top: var(--nav-h); left: 0; right: 0;
    flex-direction: column; background: rgba(255,255,255,0.98);
    backdrop-filter: blur(12px); padding: var(--sp-4) var(--sp-6); gap: 0;
    border-bottom: 1px solid var(--card-border);
    transform: translateY(-100%); opacity: 0; pointer-events: none;
    transition: transform 0.3s, opacity 0.3s;
  }
  .nav-links.open { transform: translateY(0); opacity: 1; pointer-events: auto; }
  .nav-links a { padding: var(--sp-3) 0; font-size: 1rem; border-bottom: 1px solid var(--card-border); width: 100%; }
  .nav-links a:last-child { border-bottom: none; }
}

/* Hero */
.hero {
  position: relative; padding: calc(var(--nav-h) + var(--sp-16)) 0 var(--sp-20);
  background: var(--bg-hero); color: var(--ink-on-dark);
  overflow: hidden; min-height: 480px; display: flex; align-items: center;
}
.hero-bg {
  position: absolute; inset: 0; z-index: 0;
  background-image: url('assets/img/hero.png');
  background-size: cover; background-position: center; opacity: 0.85;
}
/* Bottom-weighted scrim: lets the generated image dominate up top while
   guaranteeing the headline/tagline stay legible where the text sits. */
.hero::after {
  content: ''; position: absolute; inset: 0; z-index: 1; pointer-events: none;
  background: linear-gradient(180deg,
    rgba(27,31,46,0.20) 0%, rgba(27,31,46,0.45) 55%, rgba(27,31,46,0.85) 100%);
}
.hero-inner { position: relative; z-index: 2; }
.hero h1 { text-shadow: 0 2px 16px rgba(0,0,0,0.55); }
.hero .tagline { text-shadow: 0 1px 10px rgba(0,0,0,0.5); }
.hero h1 { color: var(--ink-on-dark); margin-bottom: var(--sp-4); }
.hero .tagline { color: rgba(240,238,232,0.85); margin-bottom: var(--sp-8); }
.hero-actions { display: flex; gap: var(--sp-4); flex-wrap: wrap; }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; gap: var(--sp-2);
  padding: var(--sp-3) var(--sp-6); font-family: var(--font-body);
  font-size: 0.9375rem; font-weight: 600; border-radius: var(--radius);
  border: 2px solid transparent; cursor: pointer;
  transition: background 0.2s, color 0.2s, border-color 0.2s, transform 0.15s;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: #fff; }
.btn-secondary { background: transparent; color: var(--ink-on-dark); border-color: rgba(240,238,232,0.4); }
.btn-secondary:hover { background: rgba(255,255,255,0.1); border-color: rgba(240,238,232,0.7); color: #fff; }

/* Sections */
.section { padding: var(--sp-20) 0; }
.section-alt { background: var(--bg-alt); }

/* Cards */
.card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius-lg); padding: var(--sp-8);
  box-shadow: var(--card-shadow); transition: box-shadow 0.3s, transform 0.3s;
}
.card:hover { box-shadow: var(--card-shadow-lg); transform: translateY(-2px); }
.card h3 { color: var(--ink); }
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: var(--sp-6); margin-top: var(--sp-8); }
@media (max-width: 640px) { .card-grid { grid-template-columns: 1fr; } .card { padding: var(--sp-6); } }

/* Code blocks */
pre {
  background: var(--code-bg); border: 1px solid var(--code-border);
  border-radius: var(--radius); padding: var(--sp-4) var(--sp-6);
  overflow-x: auto; font-family: var(--font-mono); font-size: 0.875rem;
  line-height: 1.6; color: var(--code-text); margin-bottom: var(--sp-6);
  position: relative;
}
code { font-family: var(--font-mono); font-size: 0.875em; }
p code, li code {
  background: var(--code-bg); border: 1px solid var(--code-border);
  padding: 0.125em 0.375em; border-radius: 4px; font-size: 0.85em; color: var(--code-text);
}
.copy-btn {
  position: absolute; top: var(--sp-2); right: var(--sp-2);
  background: var(--bg); border: 1px solid var(--card-border); border-radius: 6px;
  padding: var(--sp-1) var(--sp-3); font-family: var(--font-body); font-size: 0.75rem;
  color: var(--ink-muted); cursor: pointer; opacity: 0; transition: opacity 0.2s, background 0.2s;
}
pre:hover .copy-btn { opacity: 1; }
.copy-btn:hover { background: var(--bg-alt); color: var(--ink); }
.copy-btn.copied { color: #2e7d32; }

/* Gallery */
.gallery-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--sp-6); margin-top: var(--sp-8); }
.gallery-item {
  border-radius: var(--radius-lg); overflow: hidden; border: 1px solid var(--card-border);
  background: var(--card-bg); box-shadow: var(--card-shadow); transition: box-shadow 0.3s, transform 0.3s;
}
.gallery-item:hover { box-shadow: var(--card-shadow-lg); transform: translateY(-2px); }
.gallery-item img { width: 100%; aspect-ratio: 16/10; object-fit: cover; }
.gallery-item figcaption { padding: var(--sp-3) var(--sp-4); font-size: 0.875rem; color: var(--ink-2); }

/* Use-case cards (Phase 4 emits a series of .use-case-card blocks) */
.use-case-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: var(--sp-6); margin-top: var(--sp-8); }
.use-case-card {
  background: var(--card-bg); border: 1px solid var(--card-border);
  border-radius: var(--radius-lg); padding: var(--sp-6);
  box-shadow: var(--card-shadow); transition: box-shadow 0.3s, transform 0.3s;
}
.use-case-card:hover { box-shadow: var(--card-shadow-lg); transform: translateY(-2px); }
.use-case-card h3 { color: var(--ink); margin-bottom: var(--sp-3); }
.use-case-card p { margin-bottom: var(--sp-3); }
.use-case-card .audience { margin-bottom: 0; font-size: 0.875rem; color: var(--ink-muted); }
.use-case-card .audience strong { color: var(--accent); }
@media (max-width: 640px) { .use-case-grid { grid-template-columns: 1fr; } }

/* Graceful fallback when a section's content could not be generated */
.content-error { color: var(--ink-muted); font-style: italic; }

ul, ol { padding-left: var(--sp-6); margin-bottom: var(--sp-4); }
li { margin-bottom: var(--sp-2); }

/* Fade-in animation */
.fade-in { opacity: 0; transform: translateY(20px); transition: opacity 0.6s ease-out, transform 0.6s ease-out; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

/* Footer */
.site-footer { padding: var(--sp-12) 0; background: var(--bg-hero); color: var(--ink-on-dark); text-align: center; }
.site-footer p { color: rgba(240,238,232,0.65); font-size: 0.875rem; }
.site-footer a { color: var(--ink-on-dark); }
.site-footer a:hover { color: #fff; }

/* Utility */
.text-center { text-align: center; }
.text-muted { color: var(--ink-muted); }
.mt-4 { margin-top: var(--sp-4); }
.mt-8 { margin-top: var(--sp-8); }
.mb-4 { margin-bottom: var(--sp-4); }
.mb-8 { margin-bottom: var(--sp-8); }

@media print {
  .site-nav, .nav-toggle, .copy-btn { display: none !important; }
  .hero { padding-top: var(--sp-8); min-height: auto; }
  .section { padding: var(--sp-8) 0; }
  body { font-size: 11pt; }
}