:root {
  --bg: #1a2420;
  --surface: #24302a;
  --surface-2: #2c3b34;
  --line: #3d5147;
  --text: #e7eee9;
  --muted: #b7c6bc;
  --accent: #c5d5c0;
  --accent-ink: #1a2420;
  --danger: #e7c2b4;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 17px;
  line-height: 1.45;
}

body {
  min-height: 100vh;
}

.wrap {
  width: min(40rem, 100%);
  margin: 0 auto;
  padding: 1.25rem 1rem 3rem;
}

header h1 {
  margin: 0;
  font-size: 1.75rem;
  font-weight: 650;
  letter-spacing: -0.02em;
}

header p {
  margin: 0.35rem 0 0;
  color: var(--muted);
}

.modes, .choice {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  margin: 1.25rem 0 0.75rem;
}

.modes button, .choice label, button.calc, .panel {
  border-radius: 0.85rem;
}

.modes button, .choice label {
  min-height: 3rem;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--line);
  padding: 0.65rem 0.75rem;
  font: inherit;
  cursor: pointer;
}

.modes button[aria-pressed="true"], .choice input:checked + span {
  background: var(--accent);
  color: var(--accent-ink);
  border-color: var(--accent);
  font-weight: 650;
}

.choice label { position: relative; }
.choice input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}
.choice label:focus-within {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  padding: 1rem;
  margin-top: 0.75rem;
}

.panel h2 {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  margin-bottom: 0.9rem;
}

.field span, legend {
  font-weight: 600;
}

.hint, .note {
  color: var(--muted);
  font-size: 0.92rem;
  margin: 0 0 0.9rem;
}

.row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

input[type="number"] {
  width: 100%;
  min-height: 3rem;
  border-radius: 0.75rem;
  border: 1px solid var(--line);
  background: var(--surface-2);
  color: var(--text);
  font: inherit;
  padding: 0.55rem 0.75rem;
}

input:focus, button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

fieldset {
  border: 1px solid var(--line);
  border-radius: 0.85rem;
  margin: 0 0 0.9rem;
  padding: 0.75rem;
}

legend { padding: 0 0.25rem; }

button.calc {
  width: 100%;
  min-height: 3.25rem;
  border: 0;
  background: var(--accent);
  color: var(--accent-ink);
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

button.calc:disabled {
  background: #3a4a42;
  color: #8ea196;
  cursor: not-allowed;
}

.results {
  margin-top: 1rem;
}

.results h2 { margin-top: 0; }

dl {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.45rem 1rem;
  margin: 0 0 1rem;
}

dt { color: var(--muted); }
dd { margin: 0; font-variant-numeric: tabular-nums; text-align: right; }

.buy {
  font-size: 1.35rem;
  font-weight: 700;
}

.formula {
  background: var(--bg);
  border-radius: 0.75rem;
  padding: 0.85rem;
  margin: 0;
}

.hidden { display: none; }

.warn { color: var(--danger); margin: 0.5rem 0 0; }

.faq {
  margin-top: 1.25rem;
}

.faq h2 { margin-top: 0; }

.faq h3 {
  margin: 1rem 0 0.25rem;
  font-size: 1.05rem;
}

.faq p {
  margin: 0;
  color: var(--muted);
}