:root {
  --page-bg: #f6f6f2;
  --surface: #ffffff;
  --surface-muted: #f1f2ec;
  --text: #151715;
  --text-muted: #60645f;
  --border: #d8d8d0;
  --primary: #315c4f;
  --primary-dark: #172e27;
  --brand-primary: #111111;
  --brand-primary-dark: #000000;
  --brand-accent: #315c4f;
  --error: #b42318;
  --text-inverse: #ffffff;
  --focus-ring: rgba(49, 92, 79, 0.28);
  --radius-sm: 8px;
  --radius-lg: 16px;
  --shadow: 0 16px 42px rgba(24, 38, 33, 0.08);
  --content-width: 1120px;
  --body-font: Arial, "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  --heading-font: Georgia, "Times New Roman", "Noto Serif TC", serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  min-width: 0;
  margin: 0;
  color: var(--text);
  background: var(--page-bg);
  font-family: var(--body-font);
  line-height: 1.7;
}

a {
  color: inherit;
}

.skip-link {
  position: fixed;
  top: 12px;
  left: 12px;
  z-index: 10;
  transform: translateY(-160%);
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  color: #ffffff;
  background: var(--primary-dark);
  font-weight: 800;
  text-decoration: none;
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.96);
}

.site-header-inner,
.site-footer-inner,
.content-shell {
  width: min(var(--content-width), calc(100% - 32px));
  margin: 0 auto;
}

.site-header-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 24px;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0;
}

.brand,
.site-nav,
.footer-nav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
}

.brand,
.brand:visited,
.brand:hover,
.brand:active {
  gap: 10px;
  min-height: 44px;
  color: var(--brand-primary-dark);
  font-weight: 900;
  line-height: 1.2;
  text-decoration: none;
}

.brand-mark {
  width: 28px;
  height: 28px;
  border: 8px solid #111111;
  border-right-color: var(--primary);
  border-radius: 50%;
}

.brand-text {
  white-space: nowrap;
}

.site-nav {
  gap: 4px 14px;
}

.site-nav a,
.site-nav a:visited,
.footer-nav a,
.footer-nav a:visited {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  color: var(--text-muted);
  font-weight: 800;
  text-decoration: none;
}

.site-nav a:hover,
.site-nav a[aria-current="page"],
.footer-nav a:hover {
  color: var(--brand-primary);
}

.site-nav a:active,
.footer-nav a:active {
  color: var(--brand-primary-dark);
}

.nav-cta,
.button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font: inherit;
  font-weight: 900;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
}

.nav-cta,
.nav-cta:visited,
.button-primary {
  color: var(--text-inverse);
  background: var(--brand-primary);
}

.nav-cta:hover,
.button-primary:hover {
  background: var(--brand-primary-dark);
}

.button-secondary {
  border-color: var(--border);
  color: var(--brand-primary-dark);
  background: var(--surface);
}

.button-secondary:hover {
  border-color: var(--brand-primary-dark);
  color: var(--text-inverse);
  background: var(--brand-primary-dark);
}

.nav-cta:active,
.button-primary:active {
  background: var(--brand-primary-dark);
}

.button-secondary:active {
  border-color: var(--brand-primary);
  color: var(--text-inverse);
  background: var(--brand-primary);
}

.button-primary:disabled {
  border-color: #9bada6;
  color: rgba(255, 255, 255, 0.78);
  background: #9bada6;
  box-shadow: none;
  cursor: not-allowed;
}

.button-secondary:disabled {
  border-color: var(--border);
  color: #898b84;
  background: #eeeeea;
  box-shadow: none;
  cursor: not-allowed;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
#main-content:focus {
  outline: none;
  box-shadow: 0 0 0 4px var(--focus-ring);
}

.nav-cta:focus-visible,
.button:focus-visible {
  outline: 3px solid var(--brand-accent);
  outline-offset: 3px;
  box-shadow: 0 0 0 6px var(--focus-ring);
}

.brand:focus-visible,
.site-nav a:focus-visible,
.footer-nav a:focus-visible {
  outline: 3px solid var(--brand-accent);
  outline-offset: 3px;
  box-shadow: 0 0 0 6px var(--focus-ring);
}

.hero {
  padding: clamp(40px, 6vw, 72px) 0;
  border-bottom: 1px solid var(--border);
  background:
    radial-gradient(circle at 82% 18%, rgba(98, 129, 126, 0.16), transparent 34%),
    linear-gradient(135deg, #ffffff 0%, #edf3ee 100%);
}

.hero-layout {
  display: grid;
  grid-template-columns: minmax(300px, 0.82fr) minmax(0, 1.18fr);
  gap: clamp(28px, 5vw, 56px);
  align-items: center;
}

.hero-copy {
  min-width: 0;
}

.eyebrow,
.section-kicker {
  margin: 0 0 8px;
  color: var(--primary);
  font-size: 0.82rem;
  font-weight: 900;
  letter-spacing: 0.08em;
}

.hero h1,
h2,
h3 {
  font-family: var(--heading-font);
}

.hero h1 {
  max-width: 620px;
  margin: 0;
  font-size: clamp(2.15rem, 4.6vw, 3.8rem);
  line-height: 1.12;
}

.hero-lead {
  max-width: 680px;
  margin: 18px 0 0;
  color: var(--text-muted);
  font-size: clamp(1rem, 2vw, 1.16rem);
}

.hero-note {
  max-width: 580px;
  margin-top: 24px;
  padding: 20px;
  border: 1px solid rgba(49, 92, 79, 0.22);
  border-radius: var(--radius-lg);
  background: rgba(255, 255, 255, 0.8);
}

.hero-note p {
  margin: 0;
}

.hero-note-label {
  margin-bottom: 6px !important;
  color: var(--primary);
  font-size: 0.9rem;
  font-weight: 900;
}

.hero-visual {
  min-width: 0;
  margin: 0;
  overflow: hidden;
  border: 1px solid rgba(49, 92, 79, 0.2);
  border-radius: clamp(18px, 3vw, 28px);
  background: #e9eeeb;
  box-shadow: 0 24px 60px rgba(24, 38, 33, 0.14);
}

.hero-visual img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: contain;
}

.page-grid {
  display: grid;
  gap: 24px;
  padding: 32px 0 56px;
}

.panel {
  min-width: 0;
  padding: clamp(20px, 4vw, 30px);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.privacy-note,
.calculator-link-panel {
  display: grid;
  grid-template-columns: minmax(0, 0.72fr) minmax(0, 1.28fr);
  gap: 20px 32px;
  align-items: start;
}

.privacy-note h2,
.calculator-link-panel h2,
.panel-heading h2,
.explanation-card h2,
.limits-panel h2 {
  margin: 0;
  font-size: clamp(1.35rem, 3vw, 1.8rem);
  line-height: 1.25;
}

.privacy-note p,
.panel-heading > p,
.calculator-link-panel p,
.explanation-card p,
.limits-panel li {
  color: var(--text-muted);
}

.privacy-note p,
.calculator-link-panel p,
.explanation-card p {
  margin: 0;
}

.privacy-note a,
.calculator-link-panel a:not(.button) {
  color: var(--primary-dark);
  font-weight: 800;
}

.panel-heading {
  display: grid;
  gap: 8px;
  margin-bottom: 26px;
}

.form-section {
  min-width: 0;
  margin: 0;
  padding: 0 0 24px;
  border: 0;
}

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

legend {
  padding: 0;
  font-family: var(--heading-font);
  font-size: 1.24rem;
  font-weight: 700;
}

.field-grid,
.result-grid,
.explanation-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.field {
  display: grid;
  gap: 8px;
  min-width: 0;
}

.field-wide {
  grid-column: 1 / -1;
}

.field label {
  font-size: 0.95rem;
  font-weight: 900;
}

.input-unit {
  position: relative;
}

.input-unit input {
  width: 100%;
  min-height: 48px;
  padding: 10px 88px 10px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  background: #ffffff;
  font: inherit;
}

.input-unit input:focus {
  border-color: var(--primary);
}

.input-unit span {
  position: absolute;
  top: 50%;
  right: 12px;
  transform: translateY(-50%);
  color: var(--primary);
  font-size: 0.84rem;
  font-weight: 900;
  pointer-events: none;
}

.field-note {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.87rem;
  line-height: 1.55;
}

.field-error {
  margin: 0;
  color: var(--error);
  font-size: 0.87rem;
  font-weight: 800;
  line-height: 1.55;
}

input[aria-invalid="true"] {
  border-color: var(--error);
}

.form-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  padding-top: 4px;
}

.status-message {
  min-height: 24px;
  margin: 20px 0 0;
  color: var(--primary-dark);
  font-weight: 800;
}

.results-heading {
  grid-template-columns: minmax(0, 0.75fr) minmax(0, 1.25fr);
  align-items: end;
}

.results-heading > p {
  margin: 0;
}

.results-groups {
  display: grid;
  gap: 24px;
}

.result-group {
  min-width: 0;
}

.result-group + .result-group {
  padding-top: 24px;
  border-top: 1px solid var(--border);
}

.result-group h3 {
  margin: 0;
  font-size: 1.18rem;
}

.result-grid {
  margin-bottom: 0;
}

.result-card {
  min-width: 0;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-muted);
}

.result-card-emphasis {
  border-color: rgba(49, 92, 79, 0.4);
  background: #eef5ef;
}

.result-card dt {
  color: var(--text-muted);
  font-size: 0.86rem;
  font-weight: 800;
}

.result-card dd {
  margin: 6px 0 0;
}

.result-card output {
  color: var(--text);
  font-size: 1.06rem;
  font-weight: 900;
}

.explanation-card {
  box-shadow: none;
}

.explanation-card h2 {
  margin-bottom: 10px;
}

.formula-list {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-left: 20px;
  color: var(--text-muted);
}

.calculator-link-panel {
  align-items: center;
}

.calculator-link-panel .button {
  justify-self: end;
  min-width: min(100%, 220px);
  text-align: center;
}

.limits-panel {
  padding: 4px 4px 0;
}

.limits-panel h2 {
  margin-bottom: 10px;
}

.limits-panel ul {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-left: 22px;
}

.site-footer {
  border-top: 1px solid var(--border);
  background: #ffffff;
}

.site-footer-inner {
  display: grid;
  grid-template-columns: minmax(0, 0.8fr) minmax(0, 1.2fr);
  gap: 22px 36px;
  padding: 34px 0;
}

.footer-brand,
.footer-note {
  margin: 0;
}

.footer-brand {
  color: var(--brand-primary);
  font-weight: 900;
}

.footer-note {
  margin-top: 6px;
  color: var(--text-muted);
}

.footer-nav {
  justify-content: flex-end;
  gap: 2px 14px;
}

@media (max-width: 840px) {
  .hero-layout,
  .privacy-note,
  .calculator-link-panel,
  .results-heading,
  .site-footer-inner {
    grid-template-columns: 1fr;
  }

  .hero-layout {
    gap: 28px;
  }

  .hero-copy,
  .hero h1,
  .hero-lead,
  .hero-note {
    max-width: none;
  }

  .calculator-link-panel .button {
    justify-self: start;
  }

  .footer-nav {
    justify-content: flex-start;
  }
}

@media (max-width: 680px) {
  .site-header-inner {
    gap: 10px 18px;
  }

  .site-nav {
    order: 3;
    width: 100%;
  }

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

  .field-wide {
    grid-column: auto;
  }
}

@media (max-width: 520px) {
  .site-header-inner,
  .site-footer-inner,
  .content-shell {
    width: min(100% - 24px, var(--content-width));
  }

  .brand-text {
    white-space: normal;
  }

  .site-nav {
    gap: 0 12px;
  }

  .site-nav a,
  .footer-nav a {
    min-height: 40px;
    font-size: 0.9rem;
  }

  .nav-cta {
    min-height: 42px;
    padding-inline: 12px;
  }

  .hero {
    padding: 40px 0;
  }

  .hero-visual {
    border-radius: 18px;
  }

  .panel {
    padding: 20px;
  }

  .form-actions,
  .form-actions .button {
    width: 100%;
  }
}

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