/* Mechanical Symmetry: static site. One stylesheet for both languages. */
:root {
  --bg: #fbfbfa; --panel: #ffffff; --ink: #1b2430; --muted: #5a6577; --line: #e2e5ea;
  --accent: #0072b2; --accent-ink: #ffffff; --accent-soft: #e6f1f8; --warm: #d55e00; --warm-soft: #fbece0;
  --shadow: 0 1px 2px rgba(20, 30, 45, .06), 0 8px 24px rgba(20, 30, 45, .06);
  --radius: 14px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f141b; --panel: #161d27; --ink: #e8ecf2; --muted: #9aa6b8; --line: #263041;
    --accent: #56b4e9; --accent-ink: #0b1118; --accent-soft: #172636; --warm: #f0a35e; --warm-soft: #2b2015;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 8px 24px rgba(0, 0, 0, .25);
  }
}
:root[data-theme="dark"] {
  --bg: #0f141b; --panel: #161d27; --ink: #e8ecf2; --muted: #9aa6b8; --line: #263041;
  --accent: #56b4e9; --accent-ink: #0b1118; --accent-soft: #172636; --warm: #f0a35e; --warm-soft: #2b2015;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 8px 24px rgba(0, 0, 0, .25);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 76px; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 17px/1.65 var(--font); -webkit-font-smoothing: antialiased; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; display: block; }
.wrap { max-width: 1040px; margin: 0 auto; padding: 0 20px; }

/* ---------- header ---------- */
.site-header { position: sticky; top: 0; z-index: 10; background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px); border-bottom: 1px solid var(--line); }
.bar { display: flex; align-items: center; gap: 18px; min-height: 60px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; letter-spacing: .01em; color: var(--ink); }
.brand:hover { text-decoration: none; }
.brand img { width: 34px; height: 34px; flex: none; border-radius: 7px; }
.nav { display: flex; gap: 4px; margin-left: 8px; flex-wrap: wrap; }
.nav a { color: var(--muted); font-size: 15px; padding: 6px 10px; border-radius: 8px; }
.nav a:hover { color: var(--ink); background: var(--accent-soft); text-decoration: none; }
.tools { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.lang { display: inline-flex; border: 1px solid var(--line); border-radius: 999px; overflow: hidden; background: var(--panel); }
.lang a { padding: 5px 13px; font-size: 14px; font-weight: 600; color: var(--muted); }
.lang a:hover { text-decoration: none; color: var(--ink); }
.lang a[aria-current="true"] { background: var(--accent); color: var(--accent-ink); }
.iconbtn { border: 1px solid var(--line); background: var(--panel); color: var(--ink); width: 34px; height: 34px; border-radius: 999px;
  cursor: pointer; font-size: 16px; line-height: 1; }
.iconbtn:hover { background: var(--accent-soft); }

/* ---------- hero ---------- */
.hero { padding: 64px 0 40px; }
.hero-grid { display: grid; grid-template-columns: 0.85fr 1fr; gap: 40px; align-items: center; }
.eyebrow { display: inline-block; font-size: 13px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--warm);
  background: var(--warm-soft); padding: 4px 12px; border-radius: 999px; }
h1 { font-family: var(--serif); font-size: clamp(2.4rem, 5.5vw, 3.8rem); line-height: 1.08; margin: 16px 0 14px; letter-spacing: -.01em; }
.lead { font-size: 1.2rem; color: var(--muted); margin: 0 0 14px; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 24px; }
.btn { display: inline-block; padding: 11px 20px; border-radius: 10px; font-weight: 600; font-size: 16px; border: 1px solid var(--accent);
  background: var(--accent); color: var(--accent-ink); }
.btn:hover { text-decoration: none; filter: brightness(1.08); }
.btn.ghost { background: transparent; color: var(--accent); }
.btn.ghost:hover { background: var(--accent-soft); filter: none; }
.btn small { font-weight: 500; opacity: .85; margin-left: 6px; }

/* figures sit on a white tile in both themes: the drawings use dark ink */
.fig { margin: 0; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 18px 12px; box-shadow: var(--shadow); }
.fig img { margin: 0 auto; }
.fig figcaption { font-size: 14px; line-height: 1.45; color: #5a6577; margin-top: 10px; }
.fig + .fig { margin-top: 18px; }

/* ---------- sections ---------- */
section { padding: 48px 0; }
section + section { border-top: 1px solid var(--line); }
h2 { font-family: var(--serif); font-size: clamp(1.7rem, 3.4vw, 2.2rem); line-height: 1.2; margin: 0 0 18px; }
h3 { font-size: 1.2rem; line-height: 1.3; margin: 0 0 8px; }
.cols { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: start; }
.prose p { margin: 0 0 14px; }
.prose p.big { font-size: 1.12rem; }
.feature { display: grid; grid-template-columns: 1fr 1.3fr; gap: 36px; align-items: center; padding: 22px 0; }
.feature.rev { grid-template-columns: 1.3fr 1fr; }
.feature.rev .fig-col { order: -1; }
.feature .num { display: inline-flex; align-items: center; justify-content: center; width: 28px; height: 28px; border-radius: 50%;
  background: var(--accent-soft); color: var(--accent); font-weight: 700; font-size: 14px; margin-bottom: 10px; }
.feature p { margin: 0 0 10px; color: var(--muted); }
.feature p strong { color: var(--ink); }
.note { border-left: 4px solid var(--warm); background: var(--warm-soft); padding: 12px 16px; border-radius: 0 10px 10px 0; margin: 22px 0 0; font-size: .97rem; }

.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(290px, 1fr)); gap: 20px; margin-top: 22px; }
.card { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; box-shadow: var(--shadow); }
.card h3 { margin-top: 0; }
.card p { margin: 0 0 12px; color: var(--muted); }
.card ol, .card ul { margin: 0 0 14px; padding-left: 1.2em; color: var(--muted); font-size: .97rem; }
.card li { margin: 2px 0; }
.card .btn { margin: 4px 8px 4px 0; padding: 8px 14px; font-size: 15px; }
.thumb { display: block; width: 100%; aspect-ratio: 16 / 10; object-fit: cover; object-position: 100% 45%; margin: -4px 0 14px;
  border: 1px solid var(--line); border-radius: 10px; }
.tag { font-size: 12px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase; color: var(--accent); }
.banner { border-radius: var(--radius); border: 1px solid var(--line); box-shadow: var(--shadow); width: 100%; }
.banner-cap { font-size: 14px; color: var(--muted); margin: 8px 2px 0; }

/* ---------- footer ---------- */
footer { border-top: 1px solid var(--line); padding: 34px 0 46px; font-size: 14px; color: var(--muted); background: color-mix(in srgb, var(--panel) 60%, transparent); }
footer h4 { margin: 0 0 6px; font-size: 14px; color: var(--ink); }
footer p { margin: 0 0 10px; max-width: 80ch; }
.foot-row { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; margin-top: 16px; padding-top: 14px; border-top: 1px solid var(--line); }

.hero-grid > *, .cols > *, .feature > * { min-width: 0; }

/* ---------- small screens ---------- */
@media (max-width: 860px) {
  .hero { padding-top: 36px; }
  .hero-grid, .cols, .feature { grid-template-columns: 1fr; gap: 24px; }
  .feature.rev .fig-col { order: 0; }
  .nav { display: none; }
}
@media (max-width: 480px) {
  body { font-size: 16px; }
  .brand span { display: none; }
}
@media print { .site-header, .actions, .tools { display: none; } body { background: #fff; } }