/* Brand colours come from tdcvn.net's Customizer CSS: amber header, green accent. */
:root {
  --amber: #ffb300;
  --amber-ink: #8a5a00;
  --green: #5fae2e;
  --green-soft: #eef8e6;
  --red: #d9534f;
  --ink: #1f2328;
  --muted: #5f6670;
  --line: #e4e6ea;
  --bg: #f6f7f9;
  --card: #ffffff;
  --radius: 14px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --amber-ink: #ffcf5c;
    --green: #81d742;
    --green-soft: #1d2a16;
    --ink: #e8eaed;
    --muted: #a0a6ae;
    --line: #2c3138;
    --bg: #14171b;
    --card: #1c2025;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font: 16px/1.5 system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 16px;
  background: var(--amber);
}

.brand {
  color: #1f2328;
  font-weight: 800;
  font-size: 20px;
  text-decoration: none;
}

.brand span {
  font-weight: 500;
  font-size: 13px;
  margin-left: 6px;
}

.lang button {
  border: 1px solid #1f2328;
  background: transparent;
  color: #1f2328;
  padding: 4px 10px;
  font-weight: 600;
  cursor: pointer;
}

.lang button:first-child {
  border-radius: 6px 0 0 6px;
}

.lang button:last-child {
  border-radius: 0 6px 6px 0;
  border-left: 0;
}

.lang button[aria-pressed='true'] {
  background: #1f2328;
  color: var(--amber);
}

.wrap {
  max-width: 1100px;
  margin: 0 auto;
  padding: 24px 16px 48px;
}

.intro h1 {
  margin: 0 0 4px;
  font-size: clamp(24px, 4vw, 34px);
  line-height: 1.2;
}

.intro p {
  margin: 0 0 24px;
  color: var(--muted);
}

.grid {
  display: grid;
  grid-template-columns: minmax(0, 360px) minmax(0, 1fr);
  gap: 20px;
  align-items: start;
}

@media (max-width: 820px) {
  .grid {
    grid-template-columns: minmax(0, 1fr);
  }
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
}

form.card {
  display: grid;
  gap: 14px;
  position: sticky;
  top: 16px;
}

@media (max-width: 820px) {
  form.card {
    position: static;
  }
}

label > span,
legend,
summary {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
}

input,
select {
  width: 100%;
  font: inherit;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--bg);
  color: var(--ink);
}

input:focus,
select:focus {
  outline: 2px solid var(--amber);
  outline-offset: 1px;
}

fieldset {
  border: 0;
  padding: 0;
  margin: 0;
}

.segmented {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow: hidden;
}

.segmented label {
  position: relative;
}

.segmented input {
  position: absolute;
  opacity: 0;
}

.segmented span {
  display: block;
  margin: 0;
  padding: 9px 4px;
  text-align: center;
  font-size: 13px;
  cursor: pointer;
}

.segmented input:checked + span {
  background: var(--amber);
  color: #1f2328;
}

.segmented input:focus-visible + span {
  outline: 2px solid var(--ink);
  outline-offset: -2px;
}

details summary {
  cursor: pointer;
  color: var(--muted);
}

details label {
  margin-top: 8px;
  display: block;
}

.out {
  display: grid;
  gap: 16px;
}

#results {
  display: grid;
  gap: 16px;
}

#results[hidden] {
  display: none;
}

h2 {
  margin: 0 0 4px;
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.hero {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 16px;
  border-top: 4px solid var(--amber);
}

.big {
  margin: 0;
  font-size: clamp(30px, 5vw, 44px);
  font-weight: 800;
  color: var(--amber-ink);
  line-height: 1.1;
}

.mid {
  margin: 0;
  font-size: 24px;
  font-weight: 700;
}

small {
  font-size: 0.55em;
  font-weight: 600;
  color: var(--muted);
}

.note {
  margin: 4px 0 0;
  font-size: 13px;
  color: var(--muted);
}

.tiles {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.tile.green {
  background: var(--green-soft);
}

.tile.green .mid {
  color: var(--green);
}

.chart svg {
  width: 100%;
  height: auto;
  display: block;
}

.bar-neg {
  fill: var(--red);
  opacity: 0.75;
}

.bar-pos {
  fill: var(--green);
}

.axis {
  stroke: var(--muted);
  stroke-width: 1;
}

.payback {
  stroke: var(--amber);
  stroke-width: 2;
  stroke-dasharray: 4 3;
}

.payback-label {
  fill: var(--amber-ink);
  font-size: 12px;
  font-weight: 700;
}

.tick {
  fill: var(--muted);
  font-size: 11px;
}

.cta {
  display: block;
  text-align: center;
  padding: 14px;
  border-radius: 10px;
  background: var(--amber);
  color: #1f2328;
  font-weight: 700;
  text-decoration: none;
}

.cta:hover {
  filter: brightness(0.95);
}

.error {
  margin: 0;
  padding: 14px;
  border-radius: 10px;
  background: #fdecea;
  color: #8a1c17;
}

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

@media (max-width: 480px) {
  .hero,
  .tiles {
    grid-template-columns: minmax(0, 1fr);
  }
}