:root {
  --bg: #f3f6f8;
  --bg-2: #e8f1ee;
  --ink: #102017;
  --muted: #5c6b63;
  --card: #ffffff;
  --line: rgba(16, 32, 23, 0.1);
  --teal: #0f766e;
  --teal-dark: #0b5f59;
  --teal-soft: #d9f2ee;
  --shadow: 0 1px 2px rgba(16, 32, 23, 0.05), 0 18px 50px rgba(16, 32, 23, 0.08);
  --radius: 20px;
  --focus: 0 0 0 3px #ffffff, 0 0 0 6px var(--teal);
  --uw: #0284c7;
  --nw: #059669;
  --ow: #d97706;
  --ob: #dc2626;
  --font: "Segoe UI", system-ui, -apple-system, BlinkMacSystemFont, "Helvetica Neue", sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 10% -10%, var(--bg-2), transparent 55%),
    radial-gradient(900px 420px at 100% 0%, #e7eef8, transparent 50%),
    var(--bg);
  line-height: 1.65;
}

img {
  max-width: 100%;
}

a {
  color: var(--teal-dark);
}

a:hover {
  color: var(--teal);
}

.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;
}

:focus {
  outline: none;
}

:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -48px;
  z-index: 20;
  background: var(--ink);
  color: #fff;
  padding: 8px 12px;
  border-radius: 8px;
}

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

.wrap {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(14px);
  background: rgba(243, 246, 248, 0.86);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 68px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--ink);
  font-weight: 700;
  letter-spacing: -0.03em;
}

.logo-mark {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  background: var(--teal);
  color: #fff;
  font-size: 11px;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 8px 14px;
}

.nav a {
  text-decoration: none;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 600;
}

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

.hero {
  padding: 40px 0 12px;
  text-align: center;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 12px;
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.7);
  color: var(--teal-dark);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 6vw, 3.4rem);
  line-height: 1.12;
  letter-spacing: -0.045em;
}

.lede {
  max-width: 640px;
  margin: 14px auto 0;
  color: var(--muted);
  font-size: 1.08rem;
}

.calculator-section {
  padding: 20px 0 48px;
}

.calc-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: calc(var(--radius) + 4px);
  box-shadow: var(--shadow);
  padding: 22px;
}

.calc-card h2 {
  margin: 0 0 6px;
  font-size: 1.25rem;
  letter-spacing: -0.03em;
}

.calc-intro {
  margin: 0 0 22px;
  color: var(--muted);
}

.field {
  margin-bottom: 18px;
}

.field-label {
  display: block;
  margin-bottom: 8px;
  font-weight: 700;
}

.input-row {
  display: grid;
  grid-template-columns: 1fr 110px;
  gap: 10px;
}

.height-with-unit {
  display: grid;
  grid-template-columns: 1fr 110px;
  gap: 10px;
  align-items: end;
}

.imperial-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

input[type="number"],
select,
button {
  font: inherit;
}

input[type="number"],
select {
  width: 100%;
  min-height: 48px;
  padding: 10px 12px;
  border: 1px solid #d5ded9;
  border-radius: 12px;
  background: #fbfdfc;
  color: var(--ink);
}

input[type="number"]:hover,
select:hover {
  border-color: #b7c7c1;
}

.subfield span {
  display: block;
  margin-bottom: 6px;
  color: var(--muted);
  font-size: 0.85rem;
  font-weight: 600;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 8px;
}

.btn {
  min-height: 48px;
  padding: 0 18px;
  border: 0;
  border-radius: 12px;
  cursor: pointer;
  font-weight: 700;
}

.btn-primary {
  background: var(--teal);
  color: #fff;
  flex: 1 1 180px;
}

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

.btn-secondary {
  background: #eef3f1;
  color: var(--ink);
  flex: 0 1 120px;
}

.btn-secondary:hover {
  background: #e3ebe8;
}

.form-error {
  margin: 12px 0 0;
  padding: 10px 12px;
  border-radius: 12px;
  background: #fef2f2;
  color: #991b1b;
  font-weight: 600;
}

.form-error[hidden],
[hidden] {
  display: none !important;
}

.result-panel {
  margin-top: 22px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.result-placeholder {
  margin: 0;
  color: var(--muted);
  text-align: center;
}

.result-card {
  padding: 8px 0 0;
}

.result-label {
  margin: 0;
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.bmi-number {
  margin: 4px 0 0;
  text-align: center;
  font-size: clamp(3rem, 10vw, 4.4rem);
  line-height: 1;
  letter-spacing: -0.05em;
  font-variant-numeric: tabular-nums;
}

.bmi-category {
  margin: 10px 0 0;
  text-align: center;
  font-size: 1.15rem;
  font-weight: 800;
}

.result-card.is-underweight .bmi-category { color: var(--uw); }
.result-card.is-normal .bmi-category { color: var(--nw); }
.result-card.is-overweight .bmi-category { color: var(--ow); }
.result-card.is-obesity .bmi-category { color: var(--ob); }

.bmi-explanation {
  max-width: 52ch;
  margin: 12px auto 0;
  text-align: center;
  color: var(--muted);
}

.scale {
  margin-top: 22px;
}

.scale-track {
  position: relative;
  height: 14px;
  border-radius: 999px;
  overflow: visible;
  background: linear-gradient(
    90deg,
    var(--uw) 0 14%,
    var(--nw) 14% 40%,
    var(--ow) 40% 60%,
    var(--ob) 60% 100%
  );
}

.scale-marker {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 18px;
  height: 18px;
  border: 3px solid #fff;
  border-radius: 50%;
  background: var(--ink);
  transform: translate(-50%, -50%);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
  transition: left 0.25s ease;
}

.result-card.is-visible .bmi-number,
.result-card.is-visible .bmi-category {
  animation: rise 0.35s ease;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

.scale-labels {
  display: flex;
  justify-content: space-between;
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
}

.scale-legend {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
  font-size: 0.85rem;
}

.scale-legend span {
  display: inline-block;
  width: 8px;
  height: 8px;
  margin-right: 6px;
  border-radius: 50%;
}

.dot-uw { background: var(--uw); }
.dot-nw { background: var(--nw); }
.dot-ow { background: var(--ow); }
.dot-ob { background: var(--ob); }

.content {
  padding: 12px 0 64px;
}

.content section {
  margin: 0 0 28px;
  padding: 24px;
  background: rgba(255, 255, 255, 0.72);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.content h2 {
  margin: 0 0 10px;
  letter-spacing: -0.03em;
  font-size: 1.45rem;
}

.content h3 {
  margin: 22px 0 8px;
  font-size: 1.05rem;
}

.formula {
  margin: 16px 0;
  padding: 14px 16px;
  border-radius: 14px;
  background: var(--teal-soft);
  font-weight: 700;
}

.table-wrap {
  overflow-x: auto;
  margin: 16px 0 0;
}

table {
  width: 100%;
  min-width: 280px;
  border-collapse: collapse;
}

th,
td {
  padding: 12px 10px;
  border-bottom: 1px solid var(--line);
  text-align: left;
}

th {
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}

.chart {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.chart-row {
  display: grid;
  grid-template-columns: 110px 1fr auto;
  gap: 10px;
  align-items: center;
}

.bar {
  height: 12px;
  border-radius: 999px;
}

.bar-uw { width: 55%; background: var(--uw); }
.bar-nw { width: 70%; background: var(--nw); }
.bar-ow { width: 58%; background: var(--ow); }
.bar-ob { width: 85%; background: var(--ob); }

.chart-range {
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 700;
}

.faq details {
  border-top: 1px solid var(--line);
  padding: 12px 0;
}

.faq details:first-of-type {
  border-top: 0;
}

.faq summary {
  cursor: pointer;
  font-weight: 700;
  border-radius: 8px;
}

.faq details p {
  margin: 8px 0 0;
  color: var(--muted);
}

.note {
  margin-top: 16px;
  padding: 12px 14px;
  border-left: 3px solid var(--teal);
  background: #f7fbfa;
  color: var(--muted);
}

.site-footer {
  border-top: 1px solid var(--line);
  background: #0f1c18;
  color: #d7e4df;
}

.footer-inner {
  display: grid;
  gap: 24px;
  padding: 36px 0 20px;
}

.footer-brand strong {
  display: block;
  margin-bottom: 8px;
  color: #fff;
  font-size: 1.1rem;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 16px;
}

.footer-nav a,
.site-footer a {
  color: #9ee0d6;
}

.disclaimer,
.privacy,
.copyright {
  color: #b7c7c1;
  font-size: 0.92rem;
}

.copyright {
  margin: 0;
  padding-bottom: 28px;
}

@media (min-width: 768px) {
  .wrap {
    width: min(1120px, calc(100% - 48px));
  }

  .calc-card {
    padding: 32px;
  }

  .calc-grid {
    display: grid;
    grid-template-columns: 1.05fr 0.95fr;
    gap: 32px;
    align-items: start;
  }

  .result-panel {
    margin-top: 0;
    padding-top: 0;
    border-top: 0;
    border-left: 1px solid var(--line);
    padding-left: 32px;
    min-height: 100%;
  }

  .scale-legend {
    grid-template-columns: repeat(4, 1fr);
  }

  .footer-inner {
    grid-template-columns: 1.4fr 1fr;
  }
}

@media (min-width: 1024px) {
  .hero {
    padding-top: 56px;
  }

  .content section {
    padding: 32px;
  }
}

@media (max-width: 430px) {
  .input-row,
  .height-with-unit {
    grid-template-columns: 1fr;
  }

  .chart-row {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .nav {
    font-size: 0.88rem;
  }
}

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

  .scale-marker,
  .result-card.is-visible .bmi-number,
  .result-card.is-visible .bmi-category {
    animation: none;
    transition: none;
  }
}