:root {
  --bg: #f4f1ea;
  --bg-accent: #e7efe8;
  --ink: #1c2a24;
  --muted: #5c6b64;
  --line: #d5ddd7;
  --card: #ffffff;
  --primary: #1f6b4a;
  --primary-hover: #17553a;
  --primary-soft: #e8f4ee;
  --danger: #b42318;
  --shadow: 0 12px 32px rgba(28, 42, 36, 0.08);
  --radius: 16px;
  --tap: 48px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

html,
body {
  margin: 0;
  min-height: 100%;
  overflow-x: hidden;
}

body {
  font-family: "Source Sans 3", "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.5;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -40px;
  z-index: 10;
  background: var(--primary);
  color: #fff;
  padding: 8px 12px;
  border-radius: 8px;
}

.skip-link:focus {
  top: 12px;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(244, 241, 234, 0.96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.site-header-inner {
  width: min(1100px, calc(100% - 24px));
  margin: 0 auto;
  min-height: 60px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 16px;
  padding: 10px 0;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
  font-weight: 700;
  font-size: 1.02rem;
}

.brand:hover,
.brand:focus-visible {
  color: var(--primary);
}

.brand-mark {
  display: block;
  flex-shrink: 0;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
}

.site-nav a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.92rem;
  min-height: 40px;
  display: inline-flex;
  align-items: center;
}

.site-nav a:hover,
.site-nav a:focus-visible {
  color: var(--primary);
}

#calculator,
#how-it-works,
#tile-guide,
#faq {
  scroll-margin-top: 76px;
}

.page {
  width: min(1100px, calc(100% - 24px));
  margin: 0 auto;
  padding: 24px 0 56px;
}

.hero {
  margin-bottom: 20px;
}

.eyebrow {
  margin: 0 0 8px;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--primary);
}

h1 {
  margin: 0 0 10px;
  font-size: clamp(1.85rem, 6vw, 2.75rem);
  letter-spacing: -0.03em;
  line-height: 1.15;
}

.lede {
  margin: 0;
  max-width: 44rem;
  color: var(--muted);
  font-size: 1.02rem;
}

.layout {
  display: grid;
  gap: 16px;
  align-items: start;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
}

.toolbar {
  margin-bottom: 8px;
}

.segmented,
.choice-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin: 0;
  padding: 0;
  border: 0;
}

.choice-row {
  grid-template-columns: 1fr 1fr;
}

.segment,
.choice {
  display: flex;
  min-height: var(--tap);
  position: relative;
}

.segment input,
.choice input {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: 0;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  opacity: 0;
  pointer-events: none;
}

.segment span,
.choice span {
  flex: 1;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fbfcfb;
  font-weight: 600;
  text-align: center;
  padding: 8px;
}

.segment input:focus-visible + span,
.choice input:focus-visible + span {
  outline: 2px solid #8fc9ad;
  outline-offset: 2px;
}

.segment input:checked + span,
.choice input:checked + span {
  background: var(--primary-soft);
  border-color: var(--primary);
  color: var(--primary);
}

.section + .section {
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
}

.section-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: baseline;
}

h2 {
  margin: 0 0 12px;
  font-size: 1.12rem;
}

.section-kicker {
  margin: 0;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 600;
}

.subhead {
  margin: 20px 0 8px;
  font-size: 1rem;
}

.field-grid,
.dim-grid {
  display: grid;
  gap: 12px;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.field > label {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.field > label .input-row {
  font-weight: 500;
}

label,
legend {
  font-size: 0.92rem;
  font-weight: 600;
}

.dim-group {
  margin: 0;
  padding: 0;
  border: 0;
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 88px;
  gap: 8px;
}

.input-row.prefix {
  grid-template-columns: 48px 1fr;
}

input,
select,
button {
  font: inherit;
}

input,
select {
  width: 100%;
  min-height: var(--tap);
  border: 1px solid #c9d3cd;
  border-radius: 12px;
  background: #fbfcfb;
  color: var(--ink);
  padding: 0 12px;
}

input:focus,
select:focus,
button:focus-visible {
  outline: 2px solid #8fc9ad;
  outline-offset: 1px;
}

input:focus,
select:focus {
  border-color: var(--primary);
  background: #fff;
}

input.invalid,
.area-card.invalid input {
  border-color: var(--danger);
  background: #fff7f6;
}

.unit-static {
  display: grid;
  place-items: center;
  min-height: var(--tap);
  border-radius: 12px;
  background: var(--primary-soft);
  color: var(--primary);
  font-weight: 700;
  font-size: 0.88rem;
  text-align: center;
  padding: 0 6px;
}

.ft-in {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.ft-in label {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 6px;
  align-items: center;
  font-weight: 500;
  color: var(--muted);
}

.area-card {
  padding: 14px 0;
}

.area-card + .area-card {
  border-top: 1px dashed var(--line);
}

.area-card-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
}

.area-title {
  margin: 0;
  font-size: 0.98rem;
}

.hint,
.results-note,
.results-empty {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 0.9rem;
  overflow-wrap: break-word;
}

.error {
  margin: 0;
  color: var(--danger);
  font-size: 0.86rem;
}

.actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 24px;
}

.btn-primary,
.btn-secondary,
.btn-text {
  min-height: var(--tap);
  padding: 0 16px;
  border-radius: 12px;
  border: 0;
  cursor: pointer;
  font-weight: 700;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-hover);
}

.btn-secondary {
  background: #eef2ef;
  color: var(--ink);
}

.btn-secondary:hover {
  background: #e1e8e3;
}

.btn-text {
  background: transparent;
  color: var(--primary);
  min-height: 40px;
  padding: 0;
  width: fit-content;
}

.btn-text:hover {
  text-decoration: underline;
}

.btn-text:disabled {
  color: var(--muted);
  text-decoration: none;
  cursor: default;
}

.hero-result {
  padding: 16px;
  border-radius: 14px;
  background: var(--primary-soft);
  margin-bottom: 10px;
}

.hero-result.secondary {
  background: #eef2ef;
}

.hero-label {
  margin: 0;
  color: var(--primary);
  font-weight: 700;
  font-size: 0.9rem;
}

.hero-result.secondary .hero-label {
  color: var(--ink);
}

.hero-value {
  margin: 4px 0 0;
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
}

.hero-breakdown {
  margin: 8px 0 0;
  color: var(--primary);
  font-size: 0.92rem;
}

.results-list {
  margin: 8px 0 0;
}

.results-list > div {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.results-list dt {
  color: var(--muted);
  font-weight: 500;
}

.results-list dd {
  margin: 0;
  font-weight: 700;
  text-align: right;
}

.guide {
  margin-top: 40px;
  max-width: 46rem;
}

.guide section + section {
  margin-top: 28px;
}

.guide h2 {
  font-size: 1.35rem;
  margin-bottom: 10px;
}

.guide h3 {
  margin: 16px 0 8px;
  font-size: 1.05rem;
}

.guide p,
.guide li {
  color: #3d4d46;
}

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

.site-footer {
  margin-top: 36px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.9rem;
}

@media (min-width: 640px) {
  .choice-row {
    grid-template-columns: repeat(4, 1fr);
  }

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

  .actions {
    flex-direction: row;
  }

  .btn-primary {
    flex: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}

@media (min-width: 960px) {
  .page {
    width: min(1100px, calc(100% - 40px));
    padding-top: 36px;
  }

  .site-header-inner {
    width: min(1100px, calc(100% - 40px));
  }

  .layout {
    grid-template-columns: minmax(0, 1.2fr) minmax(300px, 0.8fr);
    gap: 20px;
  }

  .results {
    position: sticky;
    top: 76px;
  }

  .card {
    padding: 24px;
  }
}