:root {
  --bg: #0b1220;
  --card: #121a2b;
  --border: #1f2a44;
  --text: #f5f7fb;
  --muted: #b8c1d9;
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, var(--bg) 0%, #0f172a 100%);
}
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 1.25rem;
}
.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(18, 26, 43, 0.6);
  backdrop-filter: blur(6px);
}
.site-header h1 { margin: 0.5rem 0 0.25rem; font-size: 1.75rem; }
.subtitle { margin: 0 0 0.75rem; color: var(--muted); }
.doc-frame {
  margin: 1.5rem 0 2rem;
  padding: 0.75rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: 0 6px 24px rgba(0,0,0,0.25);
}
iframe#doc {
  display: block;
  width: 100%;
  height: min(75vh, 900px);
  border: none;
  border-radius: 8px;
  background: #fff;
}
.site-footer {
  border-top: 1px solid var(--border);
  color: var(--muted);
  background: rgba(18, 26, 43, 0.5);
}
@media (max-width: 640px) {
  .site-header h1 { font-size: 1.4rem; }
  iframe#doc { height: 70vh; }
}

/* Image block above the sheet */
.image-block {
  margin: 1.5rem 0 1rem;
  padding: 0.75rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
}

/* Row of thumbnails (multiple images) */
.image-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}
.image-row .thumb {
  max-width: 220px;
  width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 6px 24px rgba(0,0,0,0.20);
  background: #fff;
}