:root {
  --bg: #121214;
  --bg-elev: #1c1c1f;
  --bg-elev-2: #252528;
  --border: #2f2f33;
  --text: #e8e8ea;
  --text-dim: #9c9ca3;
  --accent: #319bff;
  --accent-dim: #1f6fbf;
  --highlight: #ff453a;
  --radius: 8px;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Inter", system-ui, sans-serif;
  font-size: 14px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

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

/* --- HERO --- */
.hero {
  padding: 6rem 1.5rem 4rem;
  text-align: center;
  background: radial-gradient(ellipse at top, rgba(49,155,255,0.12) 0%, transparent 60%);
}
.hero-inner { max-width: 720px; margin: 0 auto; }
.hero h1 {
  font-size: 4rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin: 0 0 0.5rem;
  background: linear-gradient(135deg, #fff 0%, #9ad0ff 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.tagline {
  font-size: 1.1rem;
  color: var(--text-dim);
  margin: 0 0 1.5rem;
  letter-spacing: 0.02em;
}
.lede {
  font-size: 1.15rem;
  color: var(--text);
  margin: 0 0 2.5rem;
  opacity: 0.85;
}
.cta {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.7rem 1.4rem;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  border: 1px solid transparent;
  background: transparent;
  color: var(--text);
  transition: background 0.15s, border-color 0.15s, transform 0.05s;
  text-decoration: none;
  font-family: inherit;
}
.btn:hover { text-decoration: none; }
.btn:active { transform: scale(0.98); }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: #4aa8ff; }
.btn-secondary { background: var(--bg-elev-2); border-color: var(--border); color: var(--text); }
.btn-secondary:hover { background: #2f2f34; }
.btn-ghost { color: var(--text-dim); }
.btn-ghost:hover { color: var(--text); }

/* --- APP --- */
.app-section {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 1.5rem 4rem;
}

.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  padding: 4rem 0;
  color: var(--text-dim);
}
.spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text { font-size: 1rem; color: var(--text); }
.loading-sub { font-size: 0.85rem; }

.ui {
  display: grid;
  grid-template-columns: 220px minmax(320px, 380px) 1fr;
  gap: 1.25rem;
  align-items: start;
}
@media (max-width: 1100px) {
  .ui { grid-template-columns: 1fr; }
}

.sidebar {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
}
.controls { display: flex; flex-direction: column; gap: 1.25rem; }
.plot-area {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  min-height: 640px;
  min-width: 0;
}
.plot { width: 100%; height: 310px; min-width: 0; }

.card {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.1rem 1.1rem;
}
.card h3 {
  margin: 0 0 0.8rem;
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-dim);
}

.dist-info {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-dim);
  line-height: 1.55;
}
.dist-info b { color: var(--text); font-weight: 600; }

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 0.85rem;
}
.label-text {
  font-size: 0.8rem;
  color: var(--text-dim);
}

select, input[type="number"] {
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  padding: 0.45rem 0.6rem;
  font-family: inherit;
  font-size: 0.95rem;
  outline: none;
}
select:focus, input[type="number"]:focus { border-color: var(--accent); }

/* --- SLIDERS --- */
.slider-row {
  display: grid;
  grid-template-columns: 80px 90px 1fr;
  gap: 0.6rem;
  align-items: center;
  margin-bottom: 0.6rem;
}
.slider-label {
  font-size: 0.85rem;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 24px;
  background: transparent;
}
input[type="range"]::-webkit-slider-runnable-track {
  height: 4px;
  background: var(--border);
  border-radius: 2px;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  background: var(--accent);
  border-radius: 50%;
  margin-top: -6px;
  cursor: pointer;
  transition: background 0.1s, transform 0.05s;
}
input[type="range"]::-webkit-slider-thumb:hover { background: #4aa8ff; }
input[type="range"]::-webkit-slider-thumb:active { transform: scale(1.1); }
input[type="range"]::-moz-range-track { height: 4px; background: var(--border); border-radius: 2px; }
input[type="range"]::-moz-range-thumb {
  width: 16px; height: 16px; background: var(--accent); border: none; border-radius: 50%; cursor: pointer;
}

/* --- TABS --- */
.tabs {
  display: flex;
  gap: 0;
  margin: -0.3rem -0.3rem 1rem;
  border-bottom: 1px solid var(--border);
  overflow-x: auto;
}
.tab {
  background: none;
  border: none;
  color: var(--text-dim);
  padding: 0.6rem 0.9rem;
  cursor: pointer;
  font-size: 0.88rem;
  font-family: inherit;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  white-space: nowrap;
  transition: color 0.1s, border-color 0.1s;
}
.tab:hover { color: var(--text); }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); }

.op-panel { display: block; }
.op-panel[hidden] { display: none; }

.result-row {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
}
.result-label {
  font-size: 0.85rem;
  color: var(--text-dim);
}
.result-value {
  font-size: 1.6rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
  font-family: "SF Mono", "Menlo", "Consolas", monospace;
}

.hint {
  font-size: 0.82rem;
  color: var(--text-dim);
  margin: 0.5rem 0 0;
  font-style: italic;
}

.sample-output {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.75rem;
  margin: 0.75rem 0;
  max-height: 180px;
  overflow: auto;
  font-family: "SF Mono", "Menlo", monospace;
  font-size: 0.85rem;
  white-space: pre-wrap;
  word-break: break-all;
}
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 0.5rem 1rem;
  font-size: 0.85rem;
  color: var(--text-dim);
}
.stat-grid div { display: flex; justify-content: space-between; }
.stat-grid b { color: var(--text); font-weight: 500; font-variant-numeric: tabular-nums; }

/* --- DOWNLOAD --- */
.download-section {
  background: var(--bg-elev);
  border-top: 1px solid var(--border);
  padding: 4rem 1.5rem;
}
.download-inner {
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
}
.download-inner h2 {
  font-size: 2rem;
  margin: 0 0 0.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}
.download-inner p {
  color: var(--text-dim);
  margin: 0 0 2rem;
  font-size: 1.05rem;
}
.download-options {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}
.quickstart {
  text-align: left;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  margin-top: 1.5rem;
}
.quickstart summary { cursor: pointer; color: var(--text); font-weight: 500; }
.quickstart pre {
  background: var(--bg-elev-2);
  padding: 0.85rem;
  border-radius: 6px;
  overflow-x: auto;
  margin: 0.75rem 0;
  font-size: 0.85rem;
}
.quickstart code { color: var(--text); }

/* --- FOOTER --- */
.footer {
  padding: 2rem 1.5rem 3rem;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.85rem;
}
.footer a { color: var(--text-dim); }
.footer a:hover { color: var(--text); }

/* Error banner */
.error {
  background: rgba(255, 69, 58, 0.1);
  border: 1px solid var(--highlight);
  border-radius: 6px;
  padding: 0.75rem;
  margin-top: 0.75rem;
  color: var(--highlight);
  font-size: 0.85rem;
}