:root {
  --bg: #0f1216;
  --paper: #171b21;
  --paper-hover: #1e232b;
  --border: rgba(224, 214, 190, 0.14);
  --border-strong: rgba(224, 214, 190, 0.28);
  --text-main: #ece5d6;
  --text-muted: #a7a99c;
  --text-dim: #767a72;
  --bronze: #c9974d;
  --bronze-strong: #e3b872;
  --teal: #4f9c93;
  --teal-strong: #6fc0b6;
  --card-radius: 14px;
  --transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  --font-serif: "Charter", "Bitstream Charter", "Sitka Text", "Cambria", Georgia, serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-label: ui-monospace, "SF Mono", "Menlo", "Consolas", monospace;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f5f2ea;
    --paper: #fffdf7;
    --paper-hover: #eee7d6;
    --border: rgba(30, 25, 15, 0.14);
    --border-strong: rgba(30, 25, 15, 0.28);
    --text-main: #201c14;
    --text-muted: #59533f;
    --text-dim: #85806c;
    --bronze: #9c6d1f;
    --bronze-strong: #7d5713;
    --teal: #24726a;
    --teal-strong: #1a544e;
  }
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg);
  color: var(--text-main);
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

a { color: inherit; }

.site-header {
  border-bottom: 1px solid var(--border);
  padding: 1.25rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1080px;
  width: 100%;
  margin: 0 auto;
}

.site-header .brand { font-weight: 600; font-size: 0.95rem; color: var(--text-main); text-decoration: none; }
.site-header .brand:hover { color: var(--bronze-strong); }

.lang-switch {
  display: flex;
  gap: 0.25rem;
  background: var(--paper);
  border: 1px solid var(--border);
  padding: 0.25rem;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 500;
}

.lang-switch a { padding: 0.25rem 0.65rem; border-radius: 9999px; text-decoration: none; color: var(--text-muted); transition: var(--transition); }
.lang-switch a.active { background: linear-gradient(135deg, var(--bronze), var(--teal)); color: #14110b; font-weight: 600; }

main { flex: 1; max-width: 860px; width: 100%; margin: 0 auto; padding: 3rem 1.5rem 5rem; }

.lead-kicker {
  font-family: var(--font-label);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-dim);
  margin-bottom: 0.9rem;
}

h1 {
  font-family: var(--font-serif);
  font-size: clamp(2.1rem, 5.5vw, 3.1rem);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.01em;
  margin-bottom: 1.2rem;
}

.deck { font-size: 1.15rem; color: var(--text-muted); max-width: 62ch; margin-bottom: 2.4rem; }

h2 { font-family: var(--font-serif); font-size: 1.5rem; font-weight: 600; margin: 2.6rem 0 1rem; }
h3 { font-family: var(--font-serif); font-size: 1.2rem; font-weight: 600; margin: 0 0 0.75rem; }

.prose p { margin-bottom: 1.1rem; max-width: 68ch; }
.prose p:last-child { margin-bottom: 0; }
.prose strong { color: var(--text-main); }
.prose em { font-style: italic; color: var(--text-main); }

/* ---- Stat hero ---- */

.stat-hero {
  border: 1px dashed var(--border-strong);
  border-radius: var(--card-radius);
  padding: 1.8rem;
  margin-bottom: 2.5rem;
  background: var(--paper);
  position: relative;
}

.stat-hero-row { display: flex; align-items: baseline; gap: 1rem; flex-wrap: wrap; }

.stat-hero-num {
  font-family: var(--font-serif);
  font-size: clamp(2.6rem, 8vw, 3.8rem);
  font-weight: 700;
  background: linear-gradient(120deg, var(--bronze-strong), var(--teal-strong));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  line-height: 1;
}

.stat-hero-sub { font-size: 0.98rem; color: var(--text-muted); max-width: 36ch; }

/* ---- Sonar instrument ---- */

.sonar {
  border: 1px solid var(--border);
  border-radius: var(--card-radius);
  background: var(--paper);
  padding: 1.6rem;
  margin: 1.8rem 0 2.5rem;
}

.sonar-title {
  font-family: var(--font-label);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-dim);
  margin-bottom: 1.1rem;
}

.sonar-body { display: grid; grid-template-columns: minmax(0, 260px) 1fr; gap: 1.6rem; align-items: center; }

@media (max-width: 620px) {
  .sonar-body { grid-template-columns: 1fr; }
}

.sonar-rings { display: flex; justify-content: center; }
.sonar-rings svg { width: 100%; height: auto; max-width: 260px; }

.ring-radius-km {
  font-family: var(--font-serif);
  font-size: 2.1rem;
  font-weight: 700;
  color: var(--bronze-strong);
}

.ring-note { font-size: 0.9rem; color: var(--text-muted); margin-top: 0.3rem; margin-bottom: 1.1rem; min-height: 2.6em; }

.sonar-slider { display: flex; flex-direction: column; gap: 0.5rem; }

.sonar-slider input[type="range"] {
  width: 100%;
  accent-color: var(--bronze);
}

.sonar-ticks {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-label);
  font-size: 0.7rem;
  color: var(--text-dim);
}

.sonar-ticks button {
  background: none;
  border: none;
  color: inherit;
  font: inherit;
  cursor: pointer;
  padding: 0.2rem 0.4rem;
  border-radius: 6px;
  transition: var(--transition);
}

.sonar-ticks button:hover, .sonar-ticks button.active { color: var(--text-main); background: var(--paper-hover); }

.method-note {
  border-top: 1px solid var(--border);
  margin-top: 3rem;
  padding-top: 1.6rem;
}

.method-note p { font-size: 0.92rem; color: var(--text-muted); margin-bottom: 0.9rem; max-width: 68ch; }

.btt-button {
  font-family: var(--font-label);
  font-size: 0.8rem;
  color: var(--text-muted);
  background: var(--paper);
  border: 1px solid var(--border);
  padding: 0.6rem 1.2rem;
  border-radius: 999px;
  cursor: pointer;
  transition: var(--transition);
}

.btt-button:hover { color: var(--text-main); border-color: var(--border-strong); }

footer {
  border-top: 1px solid var(--border);
  padding: 1.6rem 1.5rem;
  max-width: 1080px;
  width: 100%;
  margin: 0 auto;
  display: flex;
  gap: 0.5rem 1.5rem;
  flex-wrap: wrap;
  font-size: 0.85rem;
  color: var(--text-dim);
}

footer a { color: var(--text-muted); text-decoration: none; }
footer a:hover { color: var(--text-main); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}