:root {
  --bg: #10151f;
  --bg-glow: rgba(232, 158, 74, 0.08);
  --surface: #19212f;
  --surface-2: #212b3d;
  --surface-3: #2a3549;
  --text: #f3f1ea;
  --muted: #9aa3b4;
  --line: rgba(154, 163, 180, 0.22);
  --line-strong: rgba(154, 163, 180, 0.42);
  --accent: #e8974a;
  --accent-2: #c9622f;
  --accent-ink: #241405;
  --good: #56b877;
  --warn: #e6b23c;
  --danger: #e8636a;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 10px 34px rgba(0, 0, 0, 0.35);
  --wood: #c39a68;
  color-scheme: dark;
}

:root[data-theme='light'] {
  --bg: #f6f1e8;
  --bg-glow: rgba(200, 120, 40, 0.1);
  --surface: #ffffff;
  --surface-2: #f4ede1;
  --surface-3: #ece2d1;
  --text: #23262e;
  --muted: #5f6675;
  --line: rgba(95, 102, 117, 0.24);
  --line-strong: rgba(95, 102, 117, 0.42);
  --accent: #c56a1c;
  --accent-2: #a7480f;
  --accent-ink: #ffffff;
  --good: #2e8b57;
  --warn: #b3801a;
  --danger: #c53b41;
  --shadow: 0 12px 30px rgba(60, 40, 15, 0.14);
  color-scheme: light;
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    --bg: #f6f1e8;
    --bg-glow: rgba(200, 120, 40, 0.1);
    --surface: #ffffff;
    --surface-2: #f4ede1;
    --surface-3: #ece2d1;
    --text: #23262e;
    --muted: #5f6675;
    --line: rgba(95, 102, 117, 0.24);
    --line-strong: rgba(95, 102, 117, 0.42);
    --accent: #c56a1c;
    --accent-2: #a7480f;
    --accent-ink: #ffffff;
    --good: #2e8b57;
    --warn: #b3801a;
    --danger: #c53b41;
    --shadow: 0 12px 30px rgba(60, 40, 15, 0.14);
    color-scheme: light;
  }
}

* {
  box-sizing: border-box;
}

html {
  height: 100%;
}

body {
  margin: 0;
  min-height: 100%;
  background: radial-gradient(circle at 50% -8%, var(--bg-glow), transparent 45%), var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
}

h1,
h2,
h3 {
  line-height: 1.2;
}

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

.skip-link {
  position: absolute;
  left: 1rem;
  top: -3rem;
  z-index: 30;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 0.5rem 1rem;
  border-radius: 8px;
  transition: top 0.15s ease;
}

.skip-link:focus {
  top: 1rem;
}

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

/* ---------- header ---------- */

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem clamp(1rem, 4vw, 2.5rem);
  max-width: 1200px;
  margin: 0 auto;
}

.brand {
  font-size: 1.3rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-decoration: none;
  color: var(--text);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.brand span {
  color: var(--accent);
}

.brand-mark {
  font-size: 1.15rem;
}

.icon-btn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  width: 2.4rem;
  height: 2.4rem;
  border-radius: 50%;
  font-size: 1.05rem;
  line-height: 1;
  cursor: pointer;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.icon-btn:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}

.theme-icon-dark,
:root[data-theme='light'] .theme-icon-light {
  display: none;
}

:root[data-theme='light'] .theme-icon-dark {
  display: inline;
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme]) .theme-icon-light {
    display: none;
  }

  :root:not([data-theme]) .theme-icon-dark {
    display: inline;
  }
}

/* ---------- layout ---------- */

main {
  outline: none;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 clamp(1rem, 4vw, 2.5rem);
}

.hero {
  text-align: center;
  padding: 0.6rem 0 1.4rem;
}

.hero h1 {
  margin: 0.2rem 0 0.35rem;
  font-size: clamp(1.7rem, 4.4vw, 2.6rem);
  font-weight: 800;
  letter-spacing: -0.02em;
}

.hero .tagline {
  margin: 0;
  color: var(--muted);
  font-size: clamp(1rem, 2.4vw, 1.15rem);
}

.calc {
  display: grid;
  grid-template-columns: minmax(0, 380px) minmax(0, 1fr);
  gap: 1.4rem;
  align-items: start;
}

.calc > .panel,
.fieldset {
  min-width: 0;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.panel--inputs {
  padding: 1.2rem 1.2rem 1.4rem;
}

.panel--output {
  padding: 1.2rem;
  position: sticky;
  top: 1rem;
}

/* ---------- form ---------- */

.fieldset {
  border: none;
  margin: 0 0 1.1rem;
  padding: 0;
}

.fieldset > legend {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  padding: 0;
  margin-bottom: 0.6rem;
}

.field {
  margin-bottom: 0.75rem;
}

.field > label,
.field-label {
  display: block;
  font-size: 0.86rem;
  font-weight: 600;
  margin-bottom: 0.28rem;
}

.field-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.7rem;
}

.field-grid-3 {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 0.7rem;
}

.input,
select.input {
  width: 100%;
  font: inherit;
  color: var(--text);
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 0.55rem 0.65rem;
  transition: border-color 0.12s ease, box-shadow 0.12s ease;
}

.input:hover,
select.input:hover {
  border-color: var(--line-strong);
}

.input:focus,
select.input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(232, 151, 74, 0.2);
}

select.input {
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  padding-right: 1.6rem;
}

.input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

.input-wrap .field-unit,
.input-wrap .adorn {
  position: absolute;
  right: 0.6rem;
  color: var(--muted);
  font-size: 0.85rem;
  pointer-events: none;
}

.input-wrap .adorn-left {
  left: 0.6rem;
  right: auto;
}

.input-wrap.has-left .input {
  padding-left: 1.5rem;
}

.select-wrap {
  position: relative;
}

.select-wrap::after {
  content: '';
  position: absolute;
  right: 0.7rem;
  top: 50%;
  width: 0.5rem;
  height: 0.5rem;
  border-right: 2px solid var(--muted);
  border-bottom: 2px solid var(--muted);
  transform: translateY(-70%) rotate(45deg);
  pointer-events: none;
}

/* preset chips */

.presets {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.3rem;
}

.chip {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--surface-2);
  color: var(--text);
  border-radius: 999px;
  padding: 0.34rem 0.7rem;
  font: inherit;
  font-size: 0.82rem;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
  transition: border-color 0.12s ease, transform 0.12s ease, background 0.12s ease;
}

.chip:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}

.chip.is-active {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  font-weight: 700;
}

/* switches */

.switch-row {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.switch {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 600;
}

.switch input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.switch-track {
  position: relative;
  flex: none;
  width: 2.55rem;
  height: 1.45rem;
  border-radius: 999px;
  background: var(--surface-3);
  border: 1px solid var(--line);
  transition: background 0.15s ease;
}

.switch-track::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 1.1rem;
  height: 1.1rem;
  border-radius: 50%;
  background: var(--muted);
  transition: transform 0.15s ease, background 0.15s ease;
}

.switch input:checked + .switch-track {
  background: color-mix(in srgb, var(--accent) 40%, var(--surface-3));
}

.switch input:checked + .switch-track::after {
  transform: translateX(1.1rem);
  background: var(--accent);
}

.switch input:focus-visible + .switch-track {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.field-hint {
  font-size: 0.78rem;
  color: var(--muted);
  margin: 0.15rem 0 0;
}

/* ---------- 3D preview ---------- */

.preview {
  position: relative;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background:
    radial-gradient(120% 80% at 50% 120%, color-mix(in srgb, var(--accent) 12%, transparent), transparent 60%),
    linear-gradient(180deg, var(--surface-2), var(--surface-3));
  border: 1px solid var(--line);
  aspect-ratio: 16 / 11;
  min-height: 260px;
  touch-action: none;
}

#deck-canvas {
  display: block;
  width: 100%;
  height: 100%;
  cursor: grab;
  touch-action: none;
}

#deck-canvas.is-grabbing {
  cursor: grabbing;
}

.preview-toolbar {
  position: absolute;
  top: 0.55rem;
  right: 0.55rem;
  display: flex;
  gap: 0.35rem;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.view-toggle {
  appearance: none;
  border: 1px solid var(--line);
  background: color-mix(in srgb, var(--surface) 80%, transparent);
  color: var(--text);
  border-radius: 999px;
  padding: 0.25rem 0.6rem;
  font: inherit;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  backdrop-filter: blur(4px);
}

.view-toggle[aria-pressed='false'] {
  color: var(--muted);
  opacity: 0.7;
}

.view-toggle[aria-pressed='true'] {
  border-color: var(--accent);
  color: var(--accent);
}

.preview-hint {
  position: absolute;
  left: 0.7rem;
  bottom: 0.55rem;
  margin: 0;
  font-size: 0.75rem;
  color: var(--muted);
  pointer-events: none;
  background: color-mix(in srgb, var(--surface) 55%, transparent);
  padding: 0.1rem 0.45rem;
  border-radius: 6px;
}

/* ---------- cost summary ---------- */

.summary {
  margin-top: 1.1rem;
}

.summary-total {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.6rem;
  padding: 0.9rem 1.1rem;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, color-mix(in srgb, var(--accent) 18%, var(--surface-2)), var(--surface-2));
  border: 1px solid var(--line);
}

.summary-total .total-value {
  font-size: clamp(1.7rem, 5vw, 2.3rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}

.summary-total .total-label {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  display: block;
}

.summary-total .persqft {
  text-align: right;
  font-weight: 700;
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.6rem;
  margin-top: 0.7rem;
}

.summary-cell {
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.7rem;
}

.summary-cell .k {
  display: block;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

.summary-cell .v {
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.deck-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem 0.9rem;
  margin: 0.8rem 0 0;
  color: var(--muted);
  font-size: 0.86rem;
}

.deck-meta strong {
  color: var(--text);
}

.warnings {
  margin-top: 0.8rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.warning {
  margin: 0;
  font-size: 0.84rem;
  color: var(--text);
  background: color-mix(in srgb, var(--warn) 16%, var(--surface-2));
  border: 1px solid color-mix(in srgb, var(--warn) 45%, transparent);
  border-radius: var(--radius-sm);
  padding: 0.5rem 0.7rem;
}

/* ---------- material list ---------- */

.material {
  margin-top: 1.1rem;
}

.material h2 {
  font-size: 1.05rem;
  margin: 0 0 0.5rem;
}

.material-list {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.material-list th {
  text-align: left;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  font-weight: 700;
  padding: 0.4rem 0.5rem;
  border-bottom: 1px solid var(--line);
}

.material-list th.num,
.material-list td.mi-qty,
.material-list td.mi-price,
.material-list td.mi-total {
  text-align: right;
}

.material-list td {
  padding: 0.5rem 0.5rem;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.mi-label {
  display: block;
  font-weight: 600;
}

.mi-detail {
  display: block;
  color: var(--muted);
  font-size: 0.76rem;
}

.mi-qty {
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.mi-unit {
  color: var(--muted);
  font-size: 0.78rem;
}

.mi-total {
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  white-space: nowrap;
}

.price-wrap {
  display: inline-flex;
  align-items: center;
  gap: 0.1rem;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.15rem 0.4rem;
}

.price-wrap:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(232, 151, 74, 0.18);
}

.price-prefix {
  color: var(--muted);
  font-size: 0.85rem;
}

.price-input {
  width: 3.6rem;
  border: none;
  background: transparent;
  color: var(--text);
  font: inherit;
  font-size: 0.85rem;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.price-input:focus {
  outline: none;
}

.material-list tfoot td {
  border-bottom: none;
  padding-top: 0.55rem;
}

.material-list tfoot .foot-label {
  text-align: right;
  color: var(--muted);
}

.material-list tfoot .foot-total {
  text-align: right;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.material-list tfoot tr.grand .foot-label,
.material-list tfoot tr.grand .foot-total {
  color: var(--text);
  font-size: 1.05rem;
  border-top: 2px solid var(--line-strong);
}

/* ---------- actions ---------- */

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin-top: 1.1rem;
}

.btn {
  appearance: none;
  border: 1px solid var(--line);
  background: var(--surface-2);
  color: var(--text);
  font: inherit;
  font-weight: 600;
  padding: 0.6rem 1.1rem;
  border-radius: 999px;
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease, border-color 0.12s ease;
}

.btn:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}

.btn:active {
  transform: scale(0.98);
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border: none;
  color: var(--accent-ink);
  font-weight: 800;
  box-shadow: 0 6px 20px rgba(232, 151, 74, 0.28);
}

.btn-primary:hover {
  box-shadow: 0 8px 26px rgba(232, 151, 74, 0.42);
}

.btn-small {
  padding: 0.4rem 0.9rem;
  font-size: 0.85rem;
}

/* ---------- toast ---------- */

#toast {
  position: fixed;
  left: 50%;
  bottom: 1.4rem;
  transform: translate(-50%, 1.5rem);
  background: var(--text);
  color: var(--bg);
  padding: 0.65rem 1.1rem;
  border-radius: 999px;
  font-size: 0.9rem;
  font-weight: 600;
  box-shadow: var(--shadow);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
  z-index: 40;
}

#toast.is-visible {
  opacity: 1;
  transform: translate(-50%, 0);
}

/* ---------- content ---------- */

.content {
  max-width: 52rem;
  margin: 2.4rem auto 0;
  padding: 0 0 1rem;
}

.content h2 {
  font-size: 1.3rem;
  margin: 2rem 0 0.6rem;
}

.content .intro {
  font-size: 1.08rem;
  color: var(--muted);
}

.content ul,
.content ol {
  padding-left: 1.2rem;
}

.content li {
  margin: 0.45rem 0;
}

.howto ol {
  counter-reset: step;
  list-style: none;
  padding-left: 0;
}

.howto li {
  position: relative;
  padding-left: 2.4rem;
  margin: 0.7rem 0;
}

.howto li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0.05rem;
  width: 1.7rem;
  height: 1.7rem;
  display: grid;
  place-items: center;
  background: var(--accent);
  color: var(--accent-ink);
  border-radius: 50%;
  font-weight: 800;
  font-size: 0.9rem;
}

.faq details {
  border-bottom: 1px solid var(--line);
  padding: 0.6rem 0;
}

.faq summary {
  cursor: pointer;
  font-weight: 600;
}

.faq summary:hover {
  color: var(--accent);
}

.faq p {
  color: var(--muted);
  margin: 0.5rem 0 0.2rem;
}

/* ---------- footer ---------- */

.site-footer {
  border-top: 1px solid var(--line);
  margin-top: 2.4rem;
  padding: 1.5rem clamp(1rem, 4vw, 2.5rem) 2.4rem;
  font-size: 0.88rem;
  color: var(--muted);
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin: 0;
  align-items: center;
}

.footer-legal a {
  color: var(--muted);
  text-decoration: none;
}

.footer-legal a:hover {
  color: var(--accent);
}

.footer-note {
  margin: 0.7rem 0 0;
  font-size: 0.8rem;
  max-width: 52rem;
}

.noscript-note {
  text-align: center;
}

/* ---------- legal dialog & pages ---------- */

dialog {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  max-width: min(40rem, 92vw);
  max-height: 82vh;
  padding: 0;
  box-shadow: var(--shadow);
}

dialog::backdrop {
  background: rgba(8, 10, 16, 0.66);
  backdrop-filter: blur(3px);
}

.legal-body {
  padding: 1.3rem 1.6rem 1.8rem;
  overflow: auto;
  max-height: 82vh;
}

.legal-body h2,
.legal-page h2 {
  margin-top: 0;
}

.legal-body h3,
.legal-page h3 {
  font-size: 1.02rem;
  margin: 1.4rem 0 0.4rem;
}

.legal-date {
  color: var(--muted);
  font-size: 0.85rem;
}

.legal-close-row {
  display: flex;
  justify-content: flex-end;
  position: sticky;
  top: 0;
}

.legal-page {
  max-width: 44rem;
  margin: 0 auto;
  padding: 1rem clamp(1rem, 4vw, 2rem) 3rem;
}

/* ---------- task-first v2 interface ---------- */

.header-actions,
.header-nav {
  display: flex;
  align-items: center;
}

.header-actions {
  gap: 1rem;
}

.header-nav {
  gap: 1.1rem;
}

.header-nav a {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 700;
  text-decoration: none;
}

.header-nav a:hover {
  color: var(--accent);
}

.hero {
  max-width: 50rem;
  margin: 0 auto;
  padding: 1rem 0 1.55rem;
}

.hero-kicker,
.eyebrow {
  margin: 0 0 0.3rem;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.hero h1 {
  font-size: clamp(2rem, 5.2vw, 3.35rem);
  letter-spacing: -0.045em;
}

.hero .tagline {
  max-width: 42rem;
  margin-inline: auto;
}

.hero-proof {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.45rem;
  margin-top: 0.9rem;
}

.hero-proof span {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--surface) 76%, transparent);
  color: var(--muted);
  padding: 0.26rem 0.65rem;
  font-size: 0.74rem;
  font-weight: 700;
}

.calc {
  grid-template-columns: minmax(0, 392px) minmax(0, 1fr);
  gap: clamp(1rem, 2vw, 1.5rem);
}

.panel {
  overflow: clip;
}

.panel--inputs {
  position: sticky;
  top: 0.75rem;
  max-height: calc(100vh - 1.5rem);
  overflow-x: clip;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-gutter: stable;
  scrollbar-width: thin;
  padding: 1rem 1rem 1.05rem;
}

.panel--output {
  position: relative;
  top: auto;
  padding: clamp(1rem, 2vw, 1.35rem);
}

.panel-heading,
.result-heading,
.subheading,
.material-heading,
.section-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.panel-heading,
.result-heading {
  padding-bottom: 0.85rem;
  border-bottom: 1px solid var(--line);
  margin-bottom: 0.95rem;
}

.panel-heading h2,
.result-heading h2,
.subheading h3,
.material-heading h2,
.section-heading h2 {
  margin: 0;
  letter-spacing: -0.025em;
}

.panel-heading h2,
.result-heading h2 {
  font-size: 1.08rem;
}

.text-btn,
.swap-btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: 0.78rem;
  font-weight: 750;
  cursor: pointer;
}

.text-btn:hover,
.swap-btn:hover {
  color: var(--accent);
}

.fieldset--primary {
  padding-bottom: 0.8rem;
  border-bottom: 1px solid var(--line);
}

.dimension-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.65rem;
}

.dimension-tools {
  display: flex;
  justify-content: flex-end;
  min-height: 1.6rem;
  margin: -0.25rem 0 0.4rem;
}

.stepper {
  display: grid;
  grid-template-columns: 2.4rem minmax(0, 1fr) 2.4rem;
  align-items: stretch;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  overflow: hidden;
  transition: border-color 0.12s ease, box-shadow 0.12s ease;
}

.stepper:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 22%, transparent);
}

.stepper .input-wrap,
.stepper .input {
  min-width: 0;
}

.stepper .input {
  height: 2.55rem;
  border: 0;
  border-radius: 0;
  background: transparent;
  text-align: center;
  font-weight: 750;
  font-variant-numeric: tabular-nums;
  box-shadow: none;
  padding-inline: 0.25rem 1.7rem;
}

.stepper .input:focus {
  box-shadow: none;
}

.stepper-btn {
  appearance: none;
  border: 0;
  background: color-mix(in srgb, var(--surface-3) 72%, transparent);
  color: var(--text);
  font: inherit;
  font-size: 1.15rem;
  font-weight: 700;
  cursor: pointer;
}

.stepper-btn:first-child {
  border-right: 1px solid var(--line);
}

.stepper-btn:last-child {
  border-left: 1px solid var(--line);
}

.stepper-btn:hover {
  background: color-mix(in srgb, var(--accent) 16%, var(--surface-3));
  color: var(--accent);
}

.field-error {
  display: block;
  min-height: 0;
  color: var(--danger);
  font-size: 0.72rem;
  line-height: 1.35;
}

.field.has-error .stepper {
  border-color: var(--danger);
}

.field.has-error .field-error:not(:empty) {
  min-height: 1rem;
  margin-top: 0.2rem;
}

.advanced,
.assumptions {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--surface-2) 72%, transparent);
  overflow: hidden;
}

.advanced > summary,
.assumptions > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.8rem;
  list-style: none;
  cursor: pointer;
  padding: 0.78rem 0.85rem;
}

.advanced > summary::-webkit-details-marker,
.assumptions > summary::-webkit-details-marker {
  display: none;
}

.advanced summary span:first-child,
.assumptions summary span:first-child {
  display: grid;
  gap: 0.08rem;
}

.advanced summary strong,
.assumptions summary strong {
  font-size: 0.88rem;
}

.advanced summary small,
.assumptions summary small {
  color: var(--muted);
  font-size: 0.72rem;
}

.advanced-icon {
  display: grid;
  place-items: center;
  width: 1.7rem;
  height: 1.7rem;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--accent);
  font-size: 1rem;
  transition: transform 0.18s ease;
}

.advanced[open] .advanced-icon,
.assumptions[open] .advanced-icon {
  transform: rotate(45deg);
}

.advanced-body {
  border-top: 1px solid var(--line);
  padding: 0.9rem 0.85rem 0.1rem;
}

.switch span:first-child {
  display: grid;
}

.switch strong {
  font-size: 0.86rem;
}

.switch small {
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 500;
  line-height: 1.35;
}

.stair-width-field {
  margin-top: 0.85rem;
  transition: opacity 0.15s ease;
}

.stair-width-field.is-disabled {
  opacity: 0.42;
}

.input-status {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  margin: 0.8rem 0 0;
  color: var(--muted);
  font-size: 0.72rem;
}

.live-badge,
.result-state {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  white-space: nowrap;
  color: var(--good);
  font-size: 0.72rem;
  font-weight: 800;
}

.live-badge i,
.result-state i {
  width: 0.45rem;
  height: 0.45rem;
  border-radius: 50%;
  background: currentColor;
  box-shadow: 0 0 0 4px color-mix(in srgb, currentColor 13%, transparent);
}

.result-heading {
  align-items: center;
}

.summary-total {
  margin-top: 0;
  padding: 1rem 1.05rem;
  background:
    radial-gradient(circle at 82% 20%, color-mix(in srgb, var(--accent) 24%, transparent), transparent 38%),
    linear-gradient(135deg, color-mix(in srgb, var(--accent) 13%, var(--surface-2)), var(--surface-2));
}

.summary-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.summary-cell {
  min-width: 0;
}

.summary-cell .v {
  display: block;
  overflow-wrap: anywhere;
}

.deck-meta {
  justify-content: space-between;
  padding-inline: 0.1rem;
}

.preview-shell {
  margin-top: 1rem;
}

.view-tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.3rem;
  width: min(23rem, 100%);
  margin-bottom: 0.55rem;
  padding: 0.28rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface-2);
}

.view-tab {
  appearance: none;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: var(--muted);
  padding: 0.46rem 0.65rem;
  font: inherit;
  font-size: 0.78rem;
  font-weight: 800;
  cursor: pointer;
}

.view-tab span {
  margin-right: 0.25rem;
}

.view-tab:hover,
.view-tab.is-active {
  color: var(--text);
}

.view-tab.is-active {
  background: var(--surface-3);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.16);
}

.preview {
  aspect-ratio: 16 / 9;
  min-height: 330px;
}

.preview-caption {
  margin: 0.45rem 0 0;
  color: var(--muted);
  font-size: 0.76rem;
  text-align: center;
}

.warning {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
}

.warning-mark {
  display: inline-grid;
  place-items: center;
  flex: 0 0 auto;
  width: 1.15rem;
  height: 1.15rem;
  margin-top: 0.08rem;
  border-radius: 50%;
  background: var(--warn);
  color: #19130a;
  font-size: 0.72rem;
  font-weight: 900;
}

.compare,
.result-details,
.material {
  margin-top: 1.25rem;
}

.subheading,
.material-heading,
.section-heading {
  align-items: flex-end;
  margin-bottom: 0.7rem;
}

.subheading h3,
.material-heading h2,
.section-heading h2 {
  font-size: 1.04rem;
}

.subheading > p,
.material-heading > p,
.section-heading > p {
  max-width: 27rem;
  margin: 0;
  color: var(--muted);
  font-size: 0.76rem;
  text-align: right;
}

.material-comparison {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.55rem;
}

.material-card {
  appearance: none;
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  color: var(--text);
  padding: 0.68rem;
  text-align: left;
  font: inherit;
  cursor: pointer;
  transition: border-color 0.14s ease, transform 0.14s ease, background 0.14s ease;
}

.material-card:hover {
  transform: translateY(-2px);
  border-color: var(--line-strong);
}

.material-card.is-selected {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 11%, var(--surface-2));
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--accent) 28%, transparent);
}

.material-card-top {
  display: flex;
  justify-content: space-between;
  gap: 0.4rem;
}

.material-card-name {
  overflow: hidden;
  font-size: 0.78rem;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.material-current {
  border-radius: 999px;
  background: var(--accent);
  color: var(--accent-ink);
  padding: 0.08rem 0.35rem;
  font-size: 0.58rem;
  font-weight: 900;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.material-card-cost,
.material-card-meta {
  display: block;
}

.material-card-cost {
  margin-top: 0.38rem;
  font-size: 1.08rem;
  font-weight: 850;
  font-variant-numeric: tabular-nums;
}

.material-card-meta {
  color: var(--muted);
  font-size: 0.67rem;
}

.result-details {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: 0.7rem;
}

.cost-breakdown-section,
.assumptions {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--surface-2) 72%, transparent);
}

.cost-breakdown-section {
  padding: 0.8rem;
}

.cost-breakdown-section .subheading {
  margin-bottom: 0.55rem;
}

.cost-row + .cost-row {
  margin-top: 0.5rem;
}

.cost-row-heading {
  display: flex;
  justify-content: space-between;
  gap: 0.6rem;
  color: var(--muted);
  font-size: 0.7rem;
}

.cost-row-heading strong {
  color: var(--text);
  font-variant-numeric: tabular-nums;
}

.cost-row meter {
  display: block;
  width: 100%;
  height: 0.45rem;
  margin-top: 0.2rem;
  appearance: none;
  border: 0;
  background: transparent;
}

.cost-row meter::-webkit-meter-bar {
  border: 0;
  border-radius: 999px;
  background: var(--surface-3);
}

.cost-row meter::-webkit-meter-optimum-value {
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent-2), var(--accent));
}

.cost-row meter::-moz-meter-bar {
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent-2), var(--accent));
}

.assumptions > summary {
  border-bottom: 1px solid transparent;
}

.assumptions[open] > summary {
  border-bottom-color: var(--line);
}

.assumptions ul {
  display: grid;
  gap: 0;
  margin: 0;
  padding: 0 0.8rem;
  list-style: none;
}

.assumption-item {
  padding: 0.58rem 0;
  border-bottom: 1px solid var(--line);
}

.assumption-item:last-child {
  border-bottom: 0;
}

.assumption-heading {
  display: flex;
  justify-content: space-between;
  gap: 0.6rem;
  font-size: 0.72rem;
}

.assumption-heading span {
  color: var(--muted);
}

.assumption-heading strong {
  text-align: right;
}

.assumption-item p {
  margin: 0.16rem 0 0;
  color: var(--muted);
  font-size: 0.67rem;
  line-height: 1.45;
}

.material-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}

.material-list th:first-child,
.material-list td:first-child {
  padding-left: 0.7rem;
}

.material-list th:last-child,
.material-list td:last-child {
  padding-right: 0.7rem;
}

.material-list tr:last-child td {
  border-bottom: 0;
}

.mi-category {
  display: inline-block;
  margin: 0 0.35rem 0.18rem 0;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  padding: 0.03rem 0.3rem;
  font-size: 0.58rem;
  font-weight: 850;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.result-disclaimer {
  margin: 0.8rem 0 0;
  color: var(--muted);
  font-size: 0.7rem;
}

.mobile-result-bar {
  display: none;
}

.content {
  max-width: 64rem;
  margin-top: 3rem;
}

.content .intro {
  max-width: 52rem;
  margin: 0 auto 2.2rem;
  font-size: clamp(1rem, 2vw, 1.16rem);
  text-align: center;
}

.popular-sizes,
.howto,
.uses,
.method,
.faq {
  scroll-margin-top: 1rem;
}

.popular-sizes,
.method {
  margin-top: 2.2rem;
  padding: clamp(1rem, 2.5vw, 1.4rem);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.size-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.55rem;
}

.size-card {
  appearance: none;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  color: var(--text);
  padding: 0.72rem;
  text-align: left;
  font: inherit;
  cursor: pointer;
}

.size-card:hover,
.size-card.is-active {
  border-color: var(--accent);
  background: color-mix(in srgb, var(--accent) 10%, var(--surface-2));
}

.size-card strong,
.size-card span {
  display: block;
}

.size-card strong {
  font-size: 0.9rem;
}

.size-card span {
  color: var(--muted);
  font-size: 0.66rem;
}

.method-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.6rem;
}

.method-grid article {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface-2);
  padding: 0.85rem;
}

.method-grid h3 {
  margin: 0;
  font-size: 0.88rem;
}

.method-grid p,
.method-note {
  color: var(--muted);
  font-size: 0.78rem;
}

.method-grid p {
  margin: 0.28rem 0 0;
}

.method-note {
  margin: 0.8rem 0 0;
}

.method-note strong {
  color: var(--text);
}

/* ---------- responsive ---------- */

@media (max-width: 860px) {
  body {
    padding-bottom: calc(4.65rem + env(safe-area-inset-bottom));
  }

  .calc {
    grid-template-columns: minmax(0, 1fr);
  }

  .panel--inputs,
  .panel--output {
    position: static;
  }

  .panel--inputs {
    max-height: none;
    overflow: visible;
    scrollbar-gutter: auto;
  }

  .panel--inputs {
    order: 0;
  }

  .panel--output {
    order: 1;
  }

  .summary-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .mobile-result-bar {
    position: fixed;
    right: 0.75rem;
    bottom: calc(0.7rem + env(safe-area-inset-bottom));
    left: 0.75rem;
    z-index: 35;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    border: 1px solid color-mix(in srgb, var(--accent) 42%, var(--line));
    border-radius: 14px;
    background: color-mix(in srgb, var(--surface) 92%, transparent);
    color: var(--text);
    padding: 0.62rem 0.8rem;
    text-decoration: none;
    box-shadow: var(--shadow);
    backdrop-filter: blur(12px);
  }

  .mobile-result-bar span:first-child {
    display: grid;
  }

  .mobile-result-bar small {
    color: var(--muted);
    font-size: 0.64rem;
    font-weight: 700;
  }

  .mobile-result-bar strong {
    font-size: 1.15rem;
    font-variant-numeric: tabular-nums;
  }

  .mobile-result-action {
    color: var(--accent);
    font-size: 0.76rem;
    font-weight: 800;
  }
}

@media (max-width: 680px) {
  .site-header {
    padding-block: 0.75rem;
  }

  .header-nav {
    display: none;
  }

  .hero {
    padding-top: 0.55rem;
  }

  .hero-proof {
    gap: 0.35rem;
  }

  .result-details,
  .method-grid {
    grid-template-columns: 1fr;
  }

  .material-comparison {
    grid-auto-columns: minmax(10.5rem, 45vw);
    grid-auto-flow: column;
    grid-template-columns: none;
    overflow-x: auto;
    overscroll-behavior-inline: contain;
    scroll-snap-type: x proximity;
    padding-bottom: 0.25rem;
  }

  .material-card {
    scroll-snap-align: start;
  }

  .size-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .subheading,
  .material-heading,
  .section-heading {
    align-items: flex-start;
    flex-direction: column;
    gap: 0.25rem;
  }

  .subheading > p,
  .material-heading > p,
  .section-heading > p {
    text-align: left;
  }

  .material-list thead {
    display: none;
  }

  .material-list,
  .material-list tbody,
  .material-list tr,
  .material-list td {
    display: block;
    width: 100%;
  }

  .material-list tr {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    padding: 0.72rem;
    border-bottom: 1px solid var(--line);
  }

  .material-list tr:last-child {
    border-bottom: 0;
  }

  .material-list td,
  .material-list th:first-child,
  .material-list td:first-child,
  .material-list th:last-child,
  .material-list td:last-child {
    padding: 0.35rem 0.4rem;
    border: 0;
  }

  .material-list td::before {
    content: attr(data-label);
    display: block;
    margin-bottom: 0.15rem;
    color: var(--muted);
    font-size: 0.58rem;
    font-weight: 800;
    letter-spacing: 0.05em;
    text-transform: uppercase;
  }

  .material-list .mi-item {
    grid-column: 1 / -1;
    padding-bottom: 0.55rem;
    text-align: left;
  }

  .material-list .mi-item::before {
    display: none;
  }

  .material-list td.mi-qty,
  .material-list td.mi-price,
  .material-list td.mi-total {
    text-align: left;
  }

  .price-input {
    text-align: left;
  }
}

@media (max-width: 460px) {
  .site-header .brand,
  .icon-btn,
  .text-btn,
  .swap-btn,
  .chip,
  .view-tab,
  .view-toggle,
  .actions .btn,
  .faq summary,
  .footer-legal a {
    min-height: 2.75rem;
  }

  .site-header .brand,
  .faq summary,
  .footer-legal a {
    display: flex;
    align-items: center;
  }

  .icon-btn {
    width: 2.75rem;
    height: 2.75rem;
  }

  .text-btn,
  .swap-btn {
    padding-block: 0.45rem;
  }

  .chip {
    padding-block: 0.5rem;
  }

  .price-input {
    min-height: 2.5rem;
  }

  main {
    padding-inline: 0.7rem;
  }

  .site-header {
    padding-inline: 0.8rem;
  }

  .brand {
    font-size: 1.12rem;
  }

  .hero h1 {
    font-size: 2.15rem;
  }

  .hero-proof span {
    font-size: 0.68rem;
  }

  .field-grid,
  .field-grid-3 {
    grid-template-columns: 1fr;
  }

  .dimension-grid {
    gap: 0.45rem;
  }

  .stepper {
    grid-template-columns: 2.65rem minmax(0, 1fr) 2.65rem;
  }

  .stepper-btn {
    min-height: 2.75rem;
  }

  .panel--inputs,
  .panel--output {
    border-radius: 14px;
    padding: 0.85rem;
  }

  .result-heading {
    align-items: flex-start;
  }

  .result-state {
    font-size: 0;
  }

  .result-state i {
    margin-top: 0.25rem;
  }

  .summary-total .total-value {
    font-size: 1.85rem;
  }

  .summary-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.45rem;
  }

  .summary-cell {
    padding: 0.52rem;
  }

  .preview {
    min-height: 265px;
    aspect-ratio: 4 / 3;
  }

  .preview-toolbar {
    top: auto;
    right: 0.4rem;
    bottom: 0.45rem;
    left: 0.4rem;
    justify-content: center;
  }

  .preview-hint {
    display: none;
  }

  .view-toggle {
    padding-inline: 0.52rem;
  }

  .actions .btn {
    flex: 1 1 calc(50% - 0.3rem);
    padding-inline: 0.75rem;
  }

  .content {
    margin-top: 2.2rem;
  }

  .popular-sizes,
  .method {
    padding: 0.85rem;
  }
}

/* ---------- reduced motion ---------- */

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ---------- print ---------- */

@media print {
  .site-header,
  .hero .tagline,
  .hero-proof,
  .panel--inputs,
  .preview-shell,
  .compare,
  .result-details,
  .result-state,
  .actions,
  .result-disclaimer,
  .mobile-result-bar,
  .content,
  .site-footer,
  #toast,
  .preview-toolbar {
    display: none !important;
  }

  body {
    padding-bottom: 0;
    background: #fff;
    color: #000;
  }

  .calc {
    display: block;
  }

  .panel {
    box-shadow: none;
    border: none;
  }

  .panel--output {
    position: static;
    padding: 0;
  }

  .material-list th,
  .material-list td {
    border-color: #ccc;
  }

  .price-wrap {
    border: none;
    background: none;
  }

  a[href]::after {
    content: '';
  }
}