/* Blue-Gray Calm + Soft Animations */
* { box-sizing: border-box; }
:root {
  --surface: #f4f6f8;
  --panel: #ffffff;
  --text: #1f2937;
  --muted: #6b7280;
  --line: #e5e7eb;
  --accent: #5b6c8f;   /* blue-gray */
  --accent-2: #7a8aaa; /* lighter accent */
  --shadow: 0 6px 20px rgba(17, 24, 39, 0.06);
}
html, body { margin:0; }
body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  color: var(--text); background: var(--surface); line-height: 1.65;
  -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale;
}
.site-header {
  position: sticky; top: 0; z-index: 50;
  padding: 1.25rem 1rem; border-bottom: 1px solid var(--line);
  background: rgba(255,255,255,0.9); backdrop-filter: saturate(140%) blur(6px);
}
h1, h2, h3 { margin: 0.5rem 0 0.75rem; }
h1 { font-size: 1.8rem; letter-spacing: 0.2px; }
h2 { font-size: 1.35rem; color: var(--accent); }
h3 { font-size: 1.12rem; color: var(--accent-2); }
.tagline { margin: 0.25rem 0 0.75rem; color: var(--muted); }
.menu { list-style: none; display: flex; flex-wrap: wrap; gap: 0.6rem; padding:0; margin:0.25rem 0 0; }
.menu a {
  text-decoration: none; padding: 0.45rem 0.7rem; border-radius: 10px;
  border: 1px solid var(--line); background: #fff;
  transition: border-color 220ms ease, box-shadow 220ms ease, transform 220ms ease;
}
.menu a:hover, .menu a:focus { border-color: var(--accent); box-shadow: 0 6px 18px rgba(91,108,143,0.18); transform: translateY(-1px); outline: none; }
#content { max-width: 980px; margin: 0 auto; padding: 1rem; }
section {
  margin: 1.5rem 0 2rem; padding: 1.1rem 1rem; background: var(--panel);
  border: 1px solid var(--line); border-radius: 14px; box-shadow: var(--shadow);
  transition: box-shadow 240ms ease, transform 240ms ease;
}
section:hover { box-shadow: 0 10px 28px rgba(17,24,39,0.10); transform: translateY(-1px); }
pre { background: #0f172a; color: #e2e8f0; padding: 0.8rem; overflow-x: auto; border-radius: 10px; }
table { width: 100%; border-collapse: collapse; margin: 0.75rem 0 0.5rem; }
th, td { border: 1px solid var(--line); padding: 0.6rem 0.7rem; text-align: left; }
thead th { background: #f9fafb; }
caption { text-align: left; font-weight: 600; margin-bottom: 0.45rem; }
figure { margin: 0.75rem 0; }
figure img {
  width: 100%; height: auto; display: block; border-radius: 10px; border: 1px solid var(--line);
  box-shadow: 0 10px 24px rgba(17,24,39,0.08); transition: transform 250ms ease, box-shadow 250ms ease;
}
figure img:hover { transform: translateY(-2px); box-shadow: 0 16px 36px rgba(17,24,39,0.12); }
figcaption { font-size: 0.95rem; color: var(--muted); margin-top: 0.35rem; }
.checklist { list-style: none; padding: 0; margin: 0.5rem 0 0; }
.checklist li { display: flex; align-items: center; gap: 0.55rem; margin: 0.35rem 0; padding: 0.35rem 0.4rem; border-radius: 8px; transition: background 180ms ease; }
.checklist li:hover { background: #f3f4f6; }
.backtotop a { text-decoration: none; color: var(--accent); }
.site-footer { padding: 1rem; text-align: center; font-size: 0.92rem; color: var(--muted); border-top: 1px solid var(--line); background: #fff; margin-top: 1rem; }
@keyframes fadeInUp { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: translateY(0); } }
section { animation: fadeInUp 380ms ease both; }
section:nth-child(2){animation-delay:40ms;} section:nth-child(3){animation-delay:80ms;}
section:nth-child(4){animation-delay:120ms;} section:nth-child(5){animation-delay:160ms;}
section:nth-child(6){animation-delay:200ms;} section:nth-child(7){animation-delay:240ms;}
@media (max-width: 640px) {
  h1 { font-size: 1.5rem; }
  .menu { gap: 0.4rem; }
  .menu a { padding: 0.35rem 0.55rem; }
}