:root {
  --bg: #f6f5f1;
  --surface: #ffffff;
  --ink: #1d2a2e;
  --muted: #5b6b70;
  --line: #dcdcd4;
  --accent: #0f6e66;
  --accent-soft: #e3f0ed;
  --gap: #a34a12;
  --gap-soft: #fbeee3;
  --ok: #2f7a3a;
  --ok-soft: #e6f2e5;
  --error: #b3261e;
  --radius: 10px;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111718;
    --surface: #182123;
    --ink: #e6ecea;
    --muted: #9aaaa8;
    --line: #2c3a3c;
    --accent: #5cc5b6;
    --accent-soft: #1b3533;
    --gap: #f0a36b;
    --gap-soft: #3a2619;
    --ok: #86cf8f;
    --ok-soft: #1d3320;
    --error: #ff8a80;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.5 var(--font);
  -webkit-text-size-adjust: 100%;
}

.wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 16px;
}

.masthead { padding: 32px 0 24px; }

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 16px;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--accent);
}

.brand-mark {
  width: 18px;
  height: 18px;
  border-radius: 4px;
  background: linear-gradient(90deg, var(--accent) 0 45%, transparent 45% 55%, var(--accent) 55%);
}

h1 {
  margin: 0 0 8px;
  font-size: clamp(1.6rem, 4vw, 2.3rem);
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.lede {
  margin: 0;
  max-width: 60ch;
  color: var(--muted);
}

.layout {
  display: grid;
  gap: 24px;
  align-items: start;
  padding-bottom: 32px;
}

@media (min-width: 880px) {
  .layout { grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr); }
  .result { position: sticky; top: 16px; }
}

fieldset {
  margin: 0 0 16px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

legend {
  padding: 0 6px;
  font-weight: 650;
}

.hint {
  margin: 0 0 12px;
  font-size: 0.9rem;
  color: var(--muted);
}

.grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
}

label {
  display: grid;
  gap: 4px;
  font-size: 0.9rem;
  color: var(--muted);
}

.unit-input {
  display: flex;
  align-items: stretch;
}

input {
  width: 100%;
  min-width: 0;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--bg);
  color: var(--ink);
  font: inherit;
  font-variant-numeric: tabular-nums;
}

.unit-input input {
  border-top-right-radius: 0;
  border-bottom-right-radius: 0;
}

.unit {
  display: flex;
  align-items: center;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-left: 0;
  border-radius: 0 6px 6px 0;
  font-size: 0.85rem;
  white-space: nowrap;
}

input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

input[aria-invalid="true"] { border-color: var(--error); }

.result-card {
  padding: 20px;
  border-radius: var(--radius);
  background: var(--gap-soft);
  border: 1px solid var(--line);
}

.result-card.no-gap { background: var(--ok-soft); }

.result-card h2 {
  margin: 0;
  font-size: 1rem;
  font-weight: 650;
}

.headline {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 8px;
  margin: 4px 0 0;
  font-size: clamp(2.2rem, 7vw, 3rem);
  font-weight: 750;
  line-height: 1.1;
  color: var(--gap);
  font-variant-numeric: tabular-nums;
}

.no-gap .headline { color: var(--ok); }

.per {
  font-size: 1rem;
  font-weight: 500;
  color: var(--muted);
}

.sub {
  margin: 4px 0 16px;
  color: var(--muted);
}

.error {
  margin: 0 0 16px;
  font-weight: 600;
  color: var(--error);
}

.is-invalid .headline,
.is-invalid .sub,
.is-invalid .breakdown,
.is-invalid .facts { opacity: 0.35; }

.breakdown {
  width: 100%;
  border-collapse: collapse;
  font-variant-numeric: tabular-nums;
}

.breakdown th,
.breakdown td {
  padding: 6px 0;
  border-bottom: 1px solid var(--line);
  text-align: right;
  font-size: 0.95rem;
}

.breakdown th[scope="row"] {
  text-align: left;
  font-weight: 500;
}

.breakdown thead th {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--muted);
}

.breakdown td { padding-left: 12px; }

.breakdown .sum th,
.breakdown .sum td { font-weight: 650; }

.breakdown .gap th,
.breakdown .gap td {
  font-weight: 700;
  border-bottom: 0;
}

.facts {
  display: grid;
  gap: 4px;
  margin: 16px 0 0;
  font-size: 0.9rem;
}

.facts div {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}

.facts dt { color: var(--muted); }
.facts dd { margin: 0; font-variant-numeric: tabular-nums; }

.footer {
  padding-top: 8px;
  padding-bottom: 32px;
  font-size: 0.85rem;
  color: var(--muted);
}

.footer p { margin: 0 0 4px; }

.version code { font-size: 0.8rem; }

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}