:root {
  --bg: #0b1220;
  --surface: #121a2b;
  --surface-2: #1a2438;
  --border: #2a3650;
  --text: #e8eefc;
  --muted: #9aa8c7;
  --accent: #3ddc97;
  --accent-2: #5b8cff;
  --warn: #ffb020;
  --danger: #ff6b6b;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --font: "Inter", "Segoe UI", system-ui, -apple-system, sans-serif;
  --mono: "SF Mono", "Consolas", "Liberation Mono", monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font);
  background:
    radial-gradient(1200px 600px at 10% -10%, rgba(61, 220, 151, 0.12), transparent 60%),
    radial-gradient(900px 500px at 100% 0%, rgba(91, 140, 255, 0.14), transparent 55%),
    var(--bg);
  color: var(--text);
  line-height: 1.55;
  min-height: 100vh;
}

a { color: var(--accent-2); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { width: min(1080px, calc(100% - 2rem)); margin: 0 auto; }

.site-header {
  position: sticky; top: 0; z-index: 20;
  backdrop-filter: blur(12px);
  background: rgba(11, 18, 32, 0.82);
  border-bottom: 1px solid var(--border);
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: 0.9rem 0;
}
.brand { display: flex; align-items: center; gap: 0.65rem; color: var(--text); text-decoration: none; }
.brand:hover { text-decoration: none; }
.logo {
  width: 34px; height: 34px; border-radius: 10px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #041018; font-weight: 800; font-size: 0.95rem;
}
.brand-text strong { display: block; font-size: 1rem; line-height: 1.1; }
.brand-text span { display: block; color: var(--muted); font-size: 0.75rem; }

.nav-links { display: flex; align-items: center; gap: 0.85rem; flex-wrap: wrap; }
.nav-links a { color: var(--muted); font-size: 0.95rem; }
.nav-links a:hover, .nav-links a.active { color: var(--text); text-decoration: none; }
.lang-switch {
  display: inline-flex; border: 1px solid var(--border); border-radius: 999px; overflow: hidden;
}
.lang-switch a {
  padding: 0.28rem 0.7rem; color: var(--muted); font-size: 0.8rem; text-decoration: none;
}
.lang-switch a.active { background: var(--surface-2); color: var(--text); }

.hero { padding: 3rem 0 1.5rem; }
.hero h1 {
  margin: 0 0 0.75rem; font-size: clamp(1.8rem, 4vw, 2.6rem); line-height: 1.15;
}
.hero p { margin: 0; color: var(--muted); max-width: 52ch; font-size: 1.05rem; }
.hero-actions { display: flex; gap: 0.75rem; flex-wrap: wrap; margin-top: 1.4rem; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: 0.4rem; border-radius: 999px; padding: 0.7rem 1.15rem;
  border: 1px solid transparent; font-weight: 600; cursor: pointer;
  text-decoration: none; font-size: 0.95rem;
}
.btn:hover { text-decoration: none; }
.btn-primary {
  background: linear-gradient(135deg, var(--accent), #2bc48a);
  color: #041018;
}
.btn-secondary {
  background: var(--surface); color: var(--text); border-color: var(--border);
}
.btn-secondary:hover { border-color: var(--accent-2); }

.section { padding: 1.5rem 0 2.5rem; }
.section h2 { margin: 0 0 0.85rem; font-size: 1.35rem; }
.muted { color: var(--muted); }
.note {
  margin-top: 1rem; padding: 0.85rem 1rem; border-radius: 12px;
  background: rgba(255, 176, 32, 0.08); border: 1px solid rgba(255, 176, 32, 0.25);
  color: #f3d59a; font-size: 0.9rem;
}

.grid {
  display: grid; gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.15rem 1.2rem; box-shadow: var(--shadow);
}
.card h3 { margin: 0 0 0.45rem; font-size: 1.05rem; }
.card p { margin: 0; color: var(--muted); font-size: 0.92rem; }
.card a.card-link {
  display: inline-block; margin-top: 0.85rem; color: var(--accent); font-weight: 600;
  text-decoration: none;
}
.card a.card-link:hover { text-decoration: underline; }

.tool-layout {
  display: grid; gap: 1.25rem;
  grid-template-columns: 1.15fr 0.85fr;
  align-items: start;
}
@media (max-width: 820px) {
  .tool-layout { grid-template-columns: 1fr; }
  .nav-links { justify-content: flex-end; }
}

.panel {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.2rem; box-shadow: var(--shadow);
}
.panel h1 { margin: 0 0 0.35rem; font-size: 1.55rem; }
.panel .lead { color: var(--muted); margin: 0 0 1.1rem; }

.field { margin-bottom: 0.95rem; }
.field label {
  display: block; margin-bottom: 0.35rem; font-size: 0.88rem; color: var(--muted);
}
.field input, .field select {
  width: 100%; padding: 0.7rem 0.8rem; border-radius: 10px;
  border: 1px solid var(--border); background: var(--surface-2); color: var(--text);
  font-size: 1rem;
}
.field input:focus, .field select:focus {
  outline: 2px solid rgba(91, 140, 255, 0.45); border-color: var(--accent-2);
}
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; }
@media (max-width: 520px) { .field-row { grid-template-columns: 1fr; } }

.results {
  display: grid; gap: 0.7rem;
}
.result-item {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: 12px; padding: 0.85rem 0.95rem;
}
.result-item .label { color: var(--muted); font-size: 0.82rem; }
.result-item .value {
  font-size: 1.35rem; font-weight: 700; margin-top: 0.15rem;
  font-variant-numeric: tabular-nums;
}
.result-item .value.accent { color: var(--accent); }
.result-item .sub { color: var(--muted); font-size: 0.82rem; margin-top: 0.2rem; }

.formula, .faq details {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1rem 1.1rem; margin-top: 1rem;
}
.formula h2, .faq h2 { margin: 0 0 0.6rem; font-size: 1.05rem; }
.formula code, .mono {
  font-family: var(--mono); font-size: 0.9rem; color: #cde7ff;
}
.faq details { margin-top: 0.65rem; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq p { color: var(--muted); margin: 0.55rem 0 0; }

.site-footer {
  border-top: 1px solid var(--border); margin-top: 2rem; padding: 1.5rem 0 2rem;
  color: var(--muted); font-size: 0.88rem;
}
.footer-row {
  display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap;
}
.footer-links { display: flex; gap: 0.9rem; flex-wrap: wrap; }

.badge {
  display: inline-block; padding: 0.15rem 0.5rem; border-radius: 999px;
  background: rgba(61, 220, 151, 0.12); color: var(--accent);
  border: 1px solid rgba(61, 220, 151, 0.28); font-size: 0.75rem; font-weight: 600;
}
.prose h1 { margin-top: 0; }
.prose p { color: var(--muted); }
.prose ul { color: var(--muted); }