:root {
  color-scheme: light;
  --page-plane: #f2f4f8;
  --surface: #ffffff;
  --ink: #0b0b0b;
  --ink-secondary: #52514e;
  --ink-muted: #898781;
  --border: rgba(11, 11, 11, 0.10);
  --gridline: #e1e0d9;
  --baseline: #c3c2b7;
  --accent: #2a78d6;
  --accent-strong: #184f95;
  --accent-soft: #eaf1fc;
  --accent-track: #cde2fb;
  --danger: #d03b3b;
  --danger-soft: #fceceb;
  --shadow: 0 1px 2px rgba(20, 30, 50, 0.04), 0 12px 28px rgba(20, 30, 50, 0.07);
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --page-plane: #0d0d0d;
    --surface: #1a1a19;
    --ink: #ffffff;
    --ink-secondary: #c3c2b7;
    --ink-muted: #898781;
    --border: rgba(255, 255, 255, 0.10);
    --gridline: #2c2c2a;
    --baseline: #383835;
    --accent: #3987e5;
    --accent-strong: #86b6ef;
    --accent-soft: #17222f;
    --accent-track: rgba(57, 135, 229, 0.22);
    --danger: #e66767;
    --danger-soft: #2a1c1c;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.35), 0 12px 28px rgba(0, 0, 0, 0.35);
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--page-plane);
  color: var(--ink);
  -webkit-font-smoothing: antialiased;
}

.page {
  max-width: 1120px;
  margin: 0 auto;
  padding: 40px 20px 64px;
}

.header {
  text-align: center;
  margin-bottom: 36px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: var(--accent-soft);
  color: var(--accent);
}

.brand-name {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.015em;
}

.subhead {
  margin: 0;
  color: var(--ink-secondary);
  font-size: 1rem;
  max-width: 560px;
  margin-inline: auto;
}

.layout {
  display: grid;
  grid-template-columns: 1.15fr 1fr;
  gap: 20px;
  align-items: start;
}

@media (max-width: 860px) {
  .layout {
    grid-template-columns: 1fr;
  }
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
  box-shadow: var(--shadow);
}

.result-card {
  position: sticky;
  top: 20px;
}

@media (max-width: 860px) {
  .result-card {
    position: static;
  }
}

.card-title {
  margin: 0 0 20px;
  font-size: 1.05rem;
  font-weight: 700;
}

.field-group {
  margin-bottom: 24px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border);
}

.field-group:last-of-type {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.field-heading {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.step-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-size: 0.78rem;
  font-weight: 700;
  flex: none;
}

.field-label {
  font-weight: 600;
  font-size: 0.98rem;
}

/* Segmented control (population mode, confidence level) */
.segmented {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  background: var(--page-plane);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 4px;
}

.segment {
  position: relative;
  flex: 1 1 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 9px 14px;
  border-radius: 7px;
  font-size: 0.88rem;
  color: var(--ink-secondary);
  cursor: pointer;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.segment input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.segment:hover {
  color: var(--ink);
}

.segment:has(input:checked) {
  background: var(--accent);
  color: #ffffff;
  font-weight: 600;
}

.segment:has(input:focus-visible) {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.sub-field {
  margin: 14px 0 4px;
}

.sub-label {
  display: block;
  font-size: 0.85rem;
  color: var(--ink-secondary);
  margin-bottom: 6px;
}

.hidden {
  display: none !important;
}

input[type="number"] {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--page-plane);
  color: var(--ink);
  font-size: 1rem;
  font-family: inherit;
}

input[type="number"]:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 16px;
}

.slider {
  flex: 1 1 auto;
  appearance: none;
  -webkit-appearance: none;
  height: 4px;
  border-radius: 999px;
  background: var(--accent-track);
  outline: none;
}

.slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--surface);
  box-shadow: 0 0 0 1px var(--border);
  cursor: pointer;
}

.slider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--surface);
  box-shadow: 0 0 0 1px var(--border);
  cursor: pointer;
}

.input-with-suffix {
  position: relative;
  width: 100px;
  flex: none;
}

.input-with-suffix .suffix {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--ink-muted);
  pointer-events: none;
  font-size: 0.9rem;
}

.input-with-suffix input {
  padding-right: 28px;
  text-align: right;
}

.explanation {
  margin: 12px 0 0;
  font-size: 0.87rem;
  line-height: 1.6;
  color: var(--ink-secondary);
}

.explanation strong {
  color: var(--ink);
}

.error-box {
  margin-top: 16px;
  padding: 12px 14px;
  border-radius: 8px;
  background: var(--danger-soft);
  color: var(--danger);
  font-size: 0.9rem;
}

.result-hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 22px 12px 26px;
  background: var(--accent-soft);
  border-radius: 12px;
  margin-bottom: 10px;
}

.result-label {
  font-size: 0.88rem;
  color: var(--ink-secondary);
  margin-bottom: 8px;
}

.result-number {
  font-size: 3.25rem;
  font-weight: 700;
  color: var(--accent-strong);
  line-height: 1.1;
  letter-spacing: -0.02em;
  font-variant-numeric: proportional-nums;
}

.result-unit {
  font-size: 0.92rem;
  color: var(--ink-secondary);
  margin-top: 4px;
}

.result-detail {
  text-align: center;
  font-size: 0.85rem;
  color: var(--ink-secondary);
  margin: 6px 0;
}

.chart-block {
  margin-top: 28px;
}

.chart-title {
  font-size: 0.92rem;
  font-weight: 600;
  margin: 0 0 14px;
  color: var(--ink);
}

.chart-canvas-wrap {
  position: relative;
  width: 100%;
}

.chart-canvas-wrap--tall {
  height: 260px;
}

/* Meter component: single ratio (sample vs population) against a limit */
.meter-track {
  position: relative;
  width: 100%;
  height: 14px;
  border-radius: 999px;
  background: var(--accent-track);
  overflow: hidden;
}

.meter-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  border-radius: 999px;
  transition: width 0.3s ease;
}

.meter-caption {
  margin-top: 10px;
  font-size: 0.85rem;
  color: var(--ink-secondary);
  text-align: center;
}

.meter-caption strong {
  color: var(--ink);
}

.footer {
  margin-top: 36px;
  text-align: center;
  font-size: 0.8rem;
  color: var(--ink-muted);
}