/* ── Fonts ────────────────────────────────────────────────── */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500&family=JetBrains+Mono:wght@400;500&display=swap');

/* ── Reset ────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ── Base ─────────────────────────────────────────────────── */
html {
  scroll-behavior: smooth;
  background-color: var(--surface-canvas);
  color: var(--color-ink-black);
  font-family: var(--font-primary);
  font-size: var(--text-body-sm);
  line-height: var(--leading-body-sm);
  letter-spacing: var(--tracking-body-sm);
  font-weight: var(--font-weight-regular);
  -webkit-font-smoothing: antialiased;
}

body { overflow-x: hidden; }
a { color: inherit; text-decoration: none; }
ul, ol { padding-left: 1.4em; }
li { margin-bottom: 6px; }
strong { font-weight: var(--font-weight-medium); }

/* ── Nav ──────────────────────────────────────────────────── */
.bmi-nav {
  background-color: var(--surface-canvas);
  border-bottom: 1px solid var(--color-ink-black);
  height: 64px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.bmi-nav-inner {
  max-width: var(--page-max-width);
  height: 100%;
  margin: 0 auto;
  padding: 0 var(--spacing-24);
  display: flex;
  align-items: center;
  gap: var(--spacing-24);
}

.logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-12);
  color: var(--color-ink-black);
  flex-shrink: 0;
}

.logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-nav);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: -0.02em;
}

.logo-text {
  font-size: var(--text-body-sm);
  font-weight: var(--font-weight-medium);
  letter-spacing: var(--tracking-body-sm);
}

.bmi-nav-links {
  display: flex;
  gap: var(--spacing-24);
  flex: 1;
  justify-content: center;
}

.bmi-nav-link {
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
  color: var(--color-ash-gray);
  padding: 4px 0;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.bmi-nav-link:hover,
.bmi-nav-link.active {
  color: var(--color-ink-black);
  border-bottom-color: var(--color-ink-black);
}

.btn-back {
  flex-shrink: 0;
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  color: var(--color-ink-black);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-buttons);
  padding: 6px 14px;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.btn-back:hover {
  background-color: var(--color-ink-black);
  color: var(--color-paper-white);
}

/* ── Page Hero ────────────────────────────────────────────── */
.page-hero {
  background-color: var(--surface-fog-card);
  border-bottom: 1px solid var(--color-ink-black);
  padding: var(--spacing-96) var(--spacing-24);
}

.page-hero-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
}

.page-hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-6);
  margin-bottom: var(--spacing-24);
}

.meta-tag {
  display: inline-block;
  font-size: var(--text-caption);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.06em;
  color: var(--color-ink-black);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-buttons);
  padding: 4px 12px;
}

.page-hero-heading {
  font-size: var(--text-heading);
  font-weight: var(--font-weight-medium);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink-black);
  margin-bottom: var(--spacing-12);
}

.page-hero-sub {
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
  color: var(--color-ash-gray);
  max-width: 640px;
  line-height: var(--leading-body-sm);
}

/* ── Main Calculator ──────────────────────────────────────── */
.calc-main {
  padding: var(--section-gap) 0;
  background-color: var(--surface-canvas);
}

.calc-grid {
  max-width: var(--page-max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-24);
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: var(--spacing-24);
  align-items: start;
}

/* ── Panel ────────────────────────────────────────────────── */
.calc-panel {
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-cards);
  padding: var(--spacing-36);
  background-color: var(--surface-canvas);
}

.panel-label {
  font-size: var(--text-caption);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.07em;
  color: var(--color-ink-black);
  text-transform: uppercase;
  margin-bottom: var(--spacing-24);
  padding-bottom: var(--spacing-12);
  border-bottom: 1px solid var(--color-ink-black);
}

/* ── Form Fields ──────────────────────────────────────────── */
.field-group {
  margin-bottom: var(--spacing-24);
}

.field-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-12);
}

.field-label {
  display: block;
  font-size: var(--text-caption);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.06em;
  color: var(--color-ink-black);
  text-transform: uppercase;
  margin-bottom: var(--spacing-6);
}

.label-optional {
  font-weight: var(--font-weight-regular);
  color: var(--color-ash-gray);
  text-transform: none;
  letter-spacing: normal;
}

.field-input {
  width: 100%;
  height: 42px;
  background-color: var(--surface-fog-card);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-inputs);
  padding: 0 var(--spacing-12);
  font-family: var(--font-primary);
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
  color: var(--color-ink-black);
  transition: background-color 0.15s ease;
}

.field-input::placeholder { color: var(--color-ash-gray); }
.field-input:focus { outline: none; background-color: var(--surface-canvas); }

.input-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-6);
}

/* ── Toggle Group ─────────────────────────────────────────── */
.toggle-group {
  display: flex;
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-inputs);
  overflow: hidden;
}

.toggle-btn {
  flex: 1;
  height: 36px;
  background: none;
  border: none;
  font-family: var(--font-primary);
  font-size: var(--text-caption);
  font-weight: var(--font-weight-regular);
  letter-spacing: var(--tracking-caption);
  color: var(--color-ash-gray);
  cursor: pointer;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.toggle-btn:not(:last-child) {
  border-right: 1px solid var(--color-ink-black);
}

.toggle-btn.active {
  background-color: var(--color-ink-black);
  color: var(--color-paper-white);
}

.toggle-btn:hover:not(.active) {
  background-color: var(--surface-fog-card);
  color: var(--color-ink-black);
}

/* ── Form Actions ─────────────────────────────────────────── */
.form-actions {
  display: flex;
  gap: var(--spacing-12);
  margin-top: var(--spacing-12);
}

.btn-calc {
  flex: 1.3;
  height: 44px;
  background-color: var(--color-highlighter-yellow);
  color: var(--color-ink-black);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-buttons);
  font-family: var(--font-primary);
  font-size: var(--text-body-sm);
  font-weight: var(--font-weight-medium);
  letter-spacing: var(--tracking-body-sm);
  cursor: pointer;
  transition: opacity 0.15s ease;
}

.btn-calc:hover { opacity: 0.85; }

.btn-reset-form {
  flex: 0.7;
  height: 44px;
  background-color: transparent;
  color: var(--color-ink-black);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-buttons);
  font-family: var(--font-primary);
  font-size: var(--text-body-sm);
  font-weight: var(--font-weight-regular);
  letter-spacing: var(--tracking-body-sm);
  cursor: pointer;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.btn-reset-form:hover {
  background-color: var(--color-ink-black);
  color: var(--color-paper-white);
}

.form-error {
  margin-top: var(--spacing-12);
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  color: #c0392b;
  background-color: #fdf2f2;
  border: 1px solid #e8b4b4;
  border-radius: var(--radius-inputs);
  padding: 8px 12px;
}

/* ── Result Panel ─────────────────────────────────────────── */
.result-panel {
  position: sticky;
  top: 80px;
}

.result-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-12);
  padding: var(--spacing-48) var(--spacing-24);
  text-align: center;
}

.placeholder-icon {
  color: var(--color-ash-gray);
}

.placeholder-text {
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
  color: var(--color-ash-gray);
  line-height: var(--leading-body-sm);
  max-width: 260px;
}

/* Score display */
.score-block {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-12);
  padding: var(--spacing-24) 0;
}

.score-number {
  font-family: var(--font-mono);
  font-size: 72px;
  font-weight: 500;
  line-height: 1;
  letter-spacing: -2px;
  color: var(--color-ink-black);
}

.score-badge {
  display: inline-block;
  font-size: var(--text-caption);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.07em;
  text-transform: uppercase;
  padding: 5px 14px;
  border-radius: var(--radius-buttons);
  border: 1px solid var(--color-ink-black);
  color: var(--color-ink-black);
  background-color: var(--surface-fog-card);
}

.score-badge.cat-under  { background-color: #dbeafe; border-color: #3b82f6; color: #1d4ed8; }
.score-badge.cat-normal { background-color: var(--color-highlighter-yellow); border-color: var(--color-ink-black); color: var(--color-ink-black); }
.score-badge.cat-over   { background-color: #fef3c7; border-color: #d97706; color: #92400e; }
.score-badge.cat-obese  { background-color: #fee2e2; border-color: #ef4444; color: #991b1b; }

/* BMI Scale */
.scale-container {
  margin: var(--spacing-24) 0;
}

.scale-track {
  height: 10px;
  border-radius: 9999px;
  display: flex;
  position: relative;
  margin-bottom: var(--spacing-24);
  border: 1px solid var(--color-ink-black);
  overflow: visible;
}

.scale-seg {
  height: 100%;
}

.seg-under { width: 30%; background-color: #bfdbfe; border-radius: 9999px 0 0 9999px; }
.seg-normal { width: 30%; background-color: var(--color-highlighter-yellow); }
.seg-over   { width: 20%; background-color: #fde68a; }
.seg-obese  { width: 20%; background-color: #fca5a5; border-radius: 0 9999px 9999px 0; }

.scale-marker {
  position: absolute;
  top: -6px;
  width: 14px;
  height: 22px;
  background-color: var(--color-ink-black);
  border: 2px solid var(--color-paper-white);
  border-radius: 4px;
  transform: translateX(-50%);
  transition: left 0.55s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  box-shadow: 0 0 0 1px var(--color-ink-black);
}

.scale-labels {
  position: relative;
  height: 16px;
  margin-bottom: var(--spacing-6);
}

.scale-tick {
  position: absolute;
  transform: translateX(-50%);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-ash-gray);
  letter-spacing: -0.02em;
}

.scale-legend {
  display: flex;
  gap: var(--spacing-12);
  justify-content: center;
  flex-wrap: wrap;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  color: var(--color-ash-gray);
}

.legend-dot {
  width: 8px;
  height: 8px;
  border-radius: 9999px;
  border: 1px solid var(--color-ink-black);
}

.dot-under  { background-color: #bfdbfe; }
.dot-normal { background-color: var(--color-highlighter-yellow); }
.dot-over   { background-color: #fde68a; }
.dot-obese  { background-color: #fca5a5; }

/* Insight box */
.insight-box {
  background-color: var(--surface-fog-card);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-cards);
  padding: var(--spacing-12) var(--spacing-24);
  margin: var(--spacing-24) 0;
}

.insight-text {
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  line-height: var(--leading-caption);
  color: var(--color-ink-black);
}

/* Sub-metrics */
.sub-metrics {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: var(--spacing-12);
  margin-top: var(--spacing-12);
}

.sub-metric {
  background-color: var(--surface-fog-card);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-cards);
  padding: var(--spacing-12);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-6);
}

.sub-label {
  font-size: 11px;
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.06em;
  color: var(--color-ash-gray);
  text-transform: uppercase;
}

.sub-value {
  font-family: var(--font-mono);
  font-size: var(--text-body-sm);
  font-weight: 500;
  letter-spacing: -0.03em;
  color: var(--color-ink-black);
}

/* ── WHO Section ──────────────────────────────────────────── */
.who-section {
  background-color: var(--surface-fog-card);
  border-top: 1px solid var(--color-ink-black);
  border-bottom: 1px solid var(--color-ink-black);
  padding: var(--section-gap) var(--spacing-24);
}

.who-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
}

.section-header-block {
  margin-bottom: var(--spacing-48);
  max-width: 600px;
}

.section-eyebrow {
  display: block;
  font-size: var(--text-caption);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.07em;
  color: var(--color-ash-gray);
  text-transform: uppercase;
  margin-bottom: var(--spacing-12);
}

.section-h2 {
  font-size: var(--text-heading-sm);
  font-weight: var(--font-weight-medium);
  line-height: var(--leading-heading-sm);
  letter-spacing: var(--tracking-heading-sm);
  color: var(--color-ink-black);
  margin-bottom: var(--spacing-12);
}

.section-desc {
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
  color: var(--color-ash-gray);
  line-height: var(--leading-body-sm);
}

.who-table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
}

.who-table th, .who-table td {
  text-align: left;
  padding: var(--spacing-12) var(--spacing-24);
  border-bottom: 1px solid var(--color-ink-black);
}

.who-table th {
  font-size: var(--text-caption);
  font-weight: var(--font-weight-medium);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-ash-gray);
  background-color: var(--surface-canvas);
  border-top: 1px solid var(--color-ink-black);
}

.who-table tr:last-child td { border-bottom: 1px solid var(--color-ink-black); }
.who-table tr:hover td { background-color: #f9f9f9; }

.who-table .row-highlight td {
  background-color: #fffde7;
  font-weight: var(--font-weight-medium);
}

/* ── Educational Section ──────────────────────────────────── */
.edu-section {
  background-color: var(--surface-canvas);
  border-bottom: 1px solid var(--color-ink-black);
  padding: var(--section-gap) var(--spacing-24);
}

.edu-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
}

/* ── FAQ Section ──────────────────────────────────────────── */
.faq-section {
  background-color: var(--surface-fog-card);
  border-bottom: 1px solid var(--color-ink-black);
  padding: var(--section-gap) var(--spacing-24);
}

.faq-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
}

/* ── Accordion ────────────────────────────────────────────── */
.accordion {
  border-top: 1px solid var(--color-ink-black);
}

.acc-item {
  border-bottom: 1px solid var(--color-ink-black);
}

.acc-header {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: none;
  border: none;
  padding: var(--spacing-24) 0;
  font-family: var(--font-primary);
  font-size: var(--text-body-sm);
  font-weight: var(--font-weight-medium);
  letter-spacing: var(--tracking-body-sm);
  color: var(--color-ink-black);
  cursor: pointer;
  text-align: left;
  gap: var(--spacing-24);
  transition: color 0.15s ease;
}

.acc-header:hover { color: var(--color-ash-gray); }

.acc-icon {
  font-size: 20px;
  font-weight: var(--font-weight-regular);
  color: var(--color-ash-gray);
  flex-shrink: 0;
  transition: transform 0.2s ease;
}

.acc-header.open .acc-icon {
  transform: rotate(45deg);
}

.acc-body {
  display: none;
  padding: 0 0 var(--spacing-24) 0;
  font-size: var(--text-body-sm);
  letter-spacing: var(--tracking-body-sm);
  line-height: var(--leading-body-sm);
  color: var(--color-ash-gray);
}

.acc-body p { margin-bottom: var(--spacing-12); }
.acc-body p:last-child { margin-bottom: 0; }

.acc-body.open { display: block; }

.formula {
  background-color: var(--surface-fog-card);
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-inputs);
  padding: var(--spacing-12) var(--spacing-24);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  color: var(--color-ink-black);
  margin: var(--spacing-12) 0;
}

/* ── Footer ───────────────────────────────────────────────── */
.bmi-footer {
  background-color: var(--color-ink-black);
  color: var(--color-paper-white);
  padding: var(--spacing-48) var(--spacing-24);
}

.bmi-footer-inner {
  max-width: var(--page-max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-12);
}

.bmi-footer .logo { color: var(--color-paper-white); }
.bmi-footer .logo-icon { border-color: rgba(255,255,255,0.3); color: var(--color-paper-white); }
.bmi-footer .logo-text { color: var(--color-paper-white); }

.footer-note {
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  line-height: var(--leading-caption);
  color: var(--color-ash-gray);
  max-width: 680px;
}

.footer-copy {
  font-size: var(--text-caption);
  letter-spacing: var(--tracking-caption);
  color: var(--color-ash-gray);
}

/* ── Responsive ───────────────────────────────────────────── */
@media (max-width: 1024px) {
  .calc-grid { grid-template-columns: 1fr; }
  .result-panel { position: static; }
  .sub-metrics { grid-template-columns: 1fr 1fr; }
}

/* Checkbox Hack Toggle Styles */
.nav-toggle-cb {
  display: none !important;
}

.nav-toggle-btn {
  display: none;
  cursor: pointer;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 1px solid var(--color-ink-black);
  border-radius: var(--radius-nav);
  color: var(--color-ink-black);
  z-index: 2001;
  transition: all 0.15s ease;
}

.nav-toggle-btn:hover {
  background-color: var(--surface-fog-card);
}

.nav-toggle-cb:checked ~ .nav-toggle-btn {
  background-color: var(--color-ink-black);
  color: var(--color-paper-white);
  border-color: var(--color-ink-black);
}

.nav-toggle-cb:checked ~ .nav-toggle-btn .menu-open-icon {
  display: none !important;
}

.nav-toggle-cb:checked ~ .nav-toggle-btn .menu-close-icon {
  display: block !important;
}

@media (max-width: 768px) {
  .nav-toggle-btn {
    display: flex;
    order: 3;
  }

  .bmi-nav {
    height: 64px !important;
  }

  .bmi-nav-inner {
    height: 100% !important;
    flex-direction: row !important;
    justify-content: space-between !important;
    align-items: center !important;
    padding: 0 var(--spacing-16) !important;
    gap: var(--spacing-12) !important;
    flex-wrap: nowrap !important;
  }

  .bmi-nav-links {
    position: fixed !important;
    top: 0 !important;
    right: -300px !important;
    width: 280px !important;
    height: 100vh !important;
    background-color: var(--surface-canvas) !important;
    border-left: 1px solid var(--color-ink-black) !important;
    flex-direction: column !important;
    justify-content: flex-start !important;
    align-items: stretch !important;
    padding: 80px 24px 24px 24px !important;
    gap: 8px !important;
    z-index: 2000 !important;
    transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1) !important;
    box-shadow: -10px 0 30px rgba(0, 0, 0, 0.08) !important;
    margin: 0 !important;
  }

  .nav-toggle-cb:checked ~ .bmi-nav-links {
    transform: translateX(-300px) !important;
  }

  .bmi-nav-link {
    font-size: 15px !important;
    padding: 12px 16px !important;
    border-bottom: none !important;
    border-left: 3px solid transparent !important;
    width: 100% !important;
    display: block !important;
    color: var(--color-ash-gray) !important;
    transition: all 0.15s ease;
    text-align: left !important;
    white-space: normal !important;
  }

  .bmi-nav-link:hover,
  .bmi-nav-link.active {
    border-left-color: var(--color-ink-black) !important;
    background-color: var(--surface-fog-card) !important;
    color: var(--color-ink-black) !important;
  }

  .btn-back {
    font-size: 11px !important;
    padding: 4px 10px !important;
    white-space: nowrap;
    flex-shrink: 0;
  }

  .page-hero { padding: var(--spacing-48) var(--spacing-24); }
  .page-hero-heading { font-size: 32px; }
  .field-row { grid-template-columns: 1fr; }
  .sub-metrics { grid-template-columns: 1fr; }
  .who-table th, .who-table td { padding: 10px var(--spacing-12); }
}