:root {
  --ink: #162033;
  --muted: #52647f;
  --soft: #eef5fb;
  --line: #cbd8e8;
  --card: #ffffff;
  --navy: #1f3f6d;
  --navy-dark: #14233b;
  --teal: #2f8e99;
  --shadow: 0 24px 70px rgba(31, 63, 109, 0.13);
}
* { box-sizing: border-box; }
html { overflow-x: hidden; }
body {
  margin: 0;
  overflow-x: hidden;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 50% 0%, #ffffff 0, #f4f8fc 36%, #edf4fa 100%);
}
button, input, select { font: inherit; }
button { cursor: pointer; }
.site-header {
  width: min(1040px, calc(100% - 40px));
  margin: 34px auto 0;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  background: rgba(255,255,255,0.9);
  border: 1px solid var(--line);
  border-radius: 24px;
  box-shadow: var(--shadow);
}
.brand { display: flex; align-items: center; gap: 12px; min-width: 0; }
.logo {
  width: 42px; height: 42px; border-radius: 13px; display: grid; place-items: center;
  color: #fff; background: var(--navy); font-size: 14px; font-weight: 900; letter-spacing: .04em;
}
.brand strong { display: block; font-size: 15px; line-height: 1.1; }
.brand span { display: block; color: var(--muted); font-size: 13px; margin-top: 2px; }
.site-header nav { display: flex; align-items: center; gap: 10px; }
.nav-link, footer button {
  border: 0; background: transparent; color: var(--ink); font-weight: 800; padding: 10px 16px; border-radius: 999px;
}
.nav-link.active { background: var(--soft); }
.hero { text-align: center; width: min(820px, calc(100% - 36px)); margin: 74px auto 34px; }
.eyebrow { text-transform: uppercase; letter-spacing: .22em; color: #a7b4c6; font-weight: 900; font-size: 13px; margin-bottom: 16px; }
.hero h1, .static-page h1 { margin: 0; font-size: clamp(36px, 4vw, 54px); line-height: .98; letter-spacing: -0.06em; }
.hero p { margin: 16px auto 0; color: var(--muted); font-size: 18px; line-height: 1.45; max-width: 720px; }
.calculator-card {
  position: relative;
  overflow: visible;
  width: min(1040px, calc(100% - 40px));
  margin: 0 auto;
  padding: 22px;
  background: rgba(255,255,255,0.94);
  border: 1px solid var(--line);
  border-radius: 28px;
  box-shadow: var(--shadow);
}
.tabs {
  position: relative;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 8px;
  padding: 8px;
  border-radius: 20px;
  background: var(--soft);
  overflow: visible;
  z-index: 10;
}
.tab-item {
  position: relative;
  overflow: visible;
  min-height: 52px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  color: var(--ink);
}
.tab-item.active { background: #fff; box-shadow: 0 14px 34px rgba(31, 63, 109, 0.12); }
.tab-label {
  border: 0;
  background: transparent;
  color: inherit;
  font-weight: 850;
  padding: 0;
  line-height: 1.1;
}
.info-button {
  position: relative;
  z-index: 12;
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 2px solid #597397;
  color: var(--navy);
  background: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  font-family: Georgia, serif;
  font-style: italic;
  font-weight: 800;
  font-size: 13px;
  line-height: 1;
  box-shadow: 0 3px 8px rgba(31, 63, 109, 0.18);
  vertical-align: middle;
}
.info-button:hover::after,
.info-button:focus-visible::after {
  content: attr(data-tip);
  position: absolute;
  left: 50%;
  bottom: calc(100% + 12px);
  transform: translateX(-50%);
  width: max-content;
  max-width: 270px;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--line);
  background: white;
  box-shadow: 0 16px 38px rgba(31, 63, 109, 0.20);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, sans-serif;
  font-style: normal;
  font-size: 13px;
  font-weight: 800;
  line-height: 1.35;
  white-space: normal;
  pointer-events: none;
}

.form-grid .info-button:hover::after,
.form-grid .info-button:focus-visible::after {
  z-index: 9999;
}
.form-grid {
  position: relative;
  z-index: 30;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-top: 24px;
  overflow: visible;
}
.field { display: grid; gap: 8px; min-width: 0; }
.field span { font-weight: 800; font-size: 15px; color: var(--ink); }
input, select {
  width: 100%;
  min-width: 0;
  height: 58px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fff;
  color: var(--ink);
  padding: 0 16px;
  font-weight: 700;
  outline: none;
}
input:focus, select:focus { border-color: var(--navy); box-shadow: 0 0 0 3px rgba(31,63,109,0.12); }
.check-card, .holiday-toggle {
  align-self: end;
  min-height: 58px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fbfdff;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 0 14px;
  font-weight: 800;
}
.check-card input { width: 20px; height: 20px; accent-color: var(--teal); padding: 0; }
.holiday-toggle { gap: 14px; }
.holiday-toggle input { position: absolute; opacity: 0; pointer-events: none; }
.holiday-toggle b {
  width: 56px; height: 30px; border-radius: 999px; background: #9aabba; position: relative; flex: 0 0 auto;
}
.holiday-toggle b::after {
  content: ''; position: absolute; width: 24px; height: 24px; border-radius: 50%; background: #fff; left: 3px; top: 3px; transition: transform .18s ease;
}
.holiday-toggle input:checked + b { background: var(--navy); }
.holiday-toggle input:checked + b::after { transform: translateX(26px); }
.holiday-toggle span { text-align: center; line-height: 1.05; font-size: 14px; }
.result-panel {
  margin-top: 22px;
  padding: 34px;
  border-radius: 18px;
  color: #fff;
  background: linear-gradient(135deg, var(--navy-dark), var(--navy));
  border: 1px solid rgba(255,255,255,0.16);
  box-shadow: 0 30px 66px rgba(17, 43, 77, 0.30), 0 12px 24px rgba(17, 43, 77, 0.18), inset 0 1px 0 rgba(255,255,255,0.12);
  position: relative;
  overflow: hidden;
  transform: translateY(-1px);
}
.result-panel::before {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(circle at 88% 12%, rgba(255,255,255,0.10), transparent 28%), linear-gradient(180deg, rgba(255,255,255,0.025), transparent 42%);
}
.result-panel > * { position: relative; z-index: 1; }
.result-header { display: flex; align-items: flex-start; justify-content: space-between; gap: 18px; margin-bottom: 18px; }
.result-panel span { display: block; text-transform: uppercase; letter-spacing: .28em; font-size: 14px; font-weight: 900; }
.result-panel h2 { margin: 0; font-size: clamp(36px, 4.2vw, 56px); letter-spacing: -0.06em; line-height: 1.05; }
.result-panel p { margin: 18px 0 0; font-size: 16px; line-height: 1.45; }
.result-panel small { display: block; margin-top: 16px; font-size: 13px; opacity: .92; line-height: 1.4; }
.result-actions { display: flex; flex-wrap: wrap; justify-content: flex-end; gap: 8px; }
.result-actions button {
  appearance: none;
  border: 1px solid rgba(255,255,255,0.28);
  background: rgba(255,255,255,0.12);
  color: #fff;
  border-radius: 999px;
  padding: 9px 13px;
  font-weight: 850;
  font-size: 13px;
  cursor: pointer;
}
.result-actions button:hover,
.result-actions button:focus-visible { background: rgba(255,255,255,0.2); outline: none; }
.copy-toast {
  display: inline-flex;
  margin-top: 18px;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(255,255,255,0.14);
  border: 1px solid rgba(255,255,255,0.22);
  font-weight: 850;
  font-size: 13px;
}
.note { margin-top: 16px; border: 1px solid #e5c079; background: #fff8e8; color: #70501b; border-radius: 14px; padding: 14px 16px; font-weight: 700; }
.assumptions, .holiday-list, .info-grid article, .content-card {
  background: rgba(255,255,255,0.88);
  border: 1px solid var(--line);
  border-radius: 18px;
}
.assumptions { margin-top: 18px; padding: 22px; }
.assumptions h3, .holiday-list h3, .info-grid h3 { margin: 0 0 14px; font-size: 20px; }
.assumptions ul { margin: 0; padding-left: 22px; color: var(--ink); line-height: 1.55; }
.holiday-list { margin-top: 18px; padding: 22px; }
.holiday-list div { display: flex; justify-content: space-between; gap: 18px; padding: 13px 0; border-top: 1px solid #dce6f1; }
.holiday-list div:first-of-type { border-top: 0; }
.holiday-list strong { white-space: nowrap; }
.info-grid {
  width: min(1040px, calc(100% - 40px));
  margin: 34px auto 44px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}
.info-grid article { padding: 24px; }
.info-grid p { color: var(--muted); line-height: 1.55; margin: 0; font-size: 16px; }

.link-list {
  margin: 18px 0 0;
  padding-left: 20px;
  color: var(--muted);
  line-height: 1.7;
}
.link-list a {
  color: var(--navy);
  font-weight: 850;
  text-decoration: none;
}
.link-list a:hover,
.link-list a:focus-visible {
  text-decoration: underline;
}
.static-page { width: min(900px, calc(100% - 40px)); margin: 80px auto 0; }
.static-page h1 { font-size: clamp(34px, 3.8vw, 50px); margin-bottom: 18px; }
.content-card { padding: 28px; color: var(--muted); font-size: 18px; line-height: 1.6; }
.content-card p:first-child { margin-top: 0; }
.content-card p:last-child { margin-bottom: 0; }
.faq-section {
  width: min(1040px, calc(100% - 40px));
  margin: 0 auto 44px;
}
.faq-section h2 {
  margin: 0 0 16px;
  font-size: clamp(24px, 3vw, 34px);
  letter-spacing: -0.035em;
}
.faq-section details {
  background: rgba(255,255,255,0.88);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 18px 20px;
  margin-top: 12px;
}
.faq-section summary {
  cursor: pointer;
  font-weight: 900;
  color: var(--ink);
}
.faq-section p {
  margin: 12px 0 0;
  color: var(--muted);
  line-height: 1.55;
}

.source-card {
  width: min(1040px, calc(100% - 40px));
  margin: 34px auto 44px;
  padding: 28px;
  background: rgba(255,255,255,0.9);
  border: 1px solid var(--line);
  border-radius: 20px;
  box-shadow: 0 16px 46px rgba(31, 63, 109, 0.08);
}
.source-card h2 { margin: 0 0 14px; font-size: clamp(24px, 3vw, 34px); letter-spacing: -0.035em; }
.source-card h2:not(:first-child) { margin-top: 34px; }
.source-card p { color: var(--muted); line-height: 1.55; }
.source-card a { color: var(--navy); font-weight: 850; }
.source-card small { color: var(--muted); }
.year-tables { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px; align-items: start; }
.data-table-wrap { overflow-x: auto; margin-top: 18px; }
.data-table { width: 100%; border-collapse: collapse; min-width: 520px; }
.data-table th, .data-table td { padding: 12px 14px; border-bottom: 1px solid #dce6f1; text-align: left; vertical-align: top; }
.data-table th { color: var(--ink); font-size: 13px; text-transform: uppercase; letter-spacing: .05em; }
.data-table td { color: var(--muted); }
.source-table { min-width: 760px; }
.source-table td:last-child { min-width: 320px; }
.quick-date-grid, .download-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; margin-top: 22px; }
.quick-date-grid div, .download-grid a {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fbfdff;
  text-decoration: none;
}
.quick-date-grid strong, .quick-date-grid span, .download-grid strong, .download-grid span { display: block; }
.quick-date-grid span, .download-grid span { margin-top: 7px; color: var(--muted); line-height: 1.4; }
.data-note { font-size: 14px; }
.embed-preview { max-width: 720px; border: 1px solid var(--line); border-radius: 20px; overflow: hidden; background: var(--soft); }
.embed-preview iframe { display: block; width: 100%; height: 760px; border: 0; }
.code-block { overflow-x: auto; padding: 18px; border-radius: 14px; background: var(--navy-dark); color: #f5f8fc; line-height: 1.55; white-space: pre-wrap; word-break: break-word; }
.copy-code { border: 0; border-radius: 999px; padding: 12px 18px; background: var(--navy); color: #fff; font-weight: 900; }
.embed-mode { background: #f4f8fc; }
.embed-shell { padding: 14px; }
.embed-shell .calculator-card { width: 100%; margin: 0; box-shadow: none; }
.embed-credit { text-align: center; margin: 14px 0 0; }
.embed-credit a { color: var(--navy); font-weight: 850; }

footer {
  width: min(1040px, calc(100% - 40px));
  margin: 44px auto 56px;
  padding-top: 26px;
  border-top: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
footer p { margin: 8px 0 0; color: var(--muted); }
footer nav { display: flex; flex-wrap: wrap; gap: 10px; }
.help-overlay { display: none; }

@media (max-width: 960px) {
  .form-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 760px) {
  body { background: radial-gradient(circle at 50% 0%, #ffffff 0, #f4f8fc 45%, #edf4fa 100%); }
  .site-header {
    width: min(640px, calc(100% - 32px));
    margin-top: 28px;
    padding: 14px 18px 16px;
    flex-direction: column;
    gap: 14px;
    border-radius: 22px;
  }
  .brand { justify-content: center; }
  .logo { width: 46px; height: 46px; }
  .brand strong { font-size: 17px; }
  .brand span { font-size: 15px; }
  .site-header nav { width: 100%; justify-content: center; gap: 12px; }
  .nav-link { font-size: 18px; padding: 11px 20px; }
  .hero { margin: 42px auto 22px; width: min(640px, calc(100% - 28px)); }
  .eyebrow { font-size: 13px; margin-bottom: 14px; }
  .hero h1 { font-size: clamp(40px, 11.5vw, 54px); line-height: 1; letter-spacing: -0.075em; }
  .hero p { font-size: 18px; line-height: 1.38; max-width: 560px; }
  .calculator-card {
    width: min(640px, calc(100% - 28px));
    padding: 12px 12px 18px;
    border-radius: 24px;
    overflow: visible;
  }
  .tabs {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 8px;
    padding: 8px;
    border-radius: 18px;
  }
  .tab-item {
    min-height: 48px;
    width: 100%;
    gap: 6px;
    border-radius: 15px;
    justify-content: center;
    padding: 0 8px;
  }
  .tab-label { font-size: 15px; font-weight: 800; white-space: nowrap; }
  .tab-item .info-button { width: 21px; height: 21px; font-size: 15px; }
  .info-button {
    width: 22px;
    height: 22px;
    border-width: 2px;
    font-size: 15px;
    box-shadow: 0 4px 8px rgba(31, 63, 109, 0.20);
  }
  .info-button:hover::after,
  .info-button:focus-visible::after { content: none; }
  .form-grid { display: block; margin-top: 26px; }
  .field, .check-card, .holiday-toggle { margin-top: 18px; }
  .field:first-child { margin-top: 0; }
  .field span { font-size: 15px; line-height: 1.2; font-weight: 800; }
  input, select {
    height: 60px;
    border-radius: 16px;
    font-size: 16px;
    font-weight: 650;
    padding: 0 16px;
    max-width: 100%;
  }
  input[type="date"] { appearance: none; -webkit-appearance: none; text-align: left; }
  .check-card {
    min-height: 60px;
    justify-content: flex-start;
    padding: 0 16px;
    font-size: 15px;
  }
  .check-card input { width: 27px; height: 27px; }
  .holiday-toggle {
    min-height: 66px;
    justify-content: space-between;
    gap: 10px;
    padding: 0 16px;
    width: 100%;
  }
  .holiday-toggle span { font-size: 14px; line-height: 1.05; max-width: 37%; }
  .holiday-toggle b { width: 64px; height: 36px; }
  .holiday-toggle b::after { width: 30px; height: 30px; }
  .holiday-toggle input:checked + b::after { transform: translateX(28px); }
  .result-panel { padding: 30px 26px; border-radius: 18px; margin-top: 26px; box-shadow: 0 22px 46px rgba(17,43,77,0.24), 0 8px 18px rgba(17,43,77,0.16), inset 0 1px 0 rgba(255,255,255,0.12); }
  .result-header { flex-direction: column; gap: 14px; }
  .result-actions { justify-content: flex-start; }
  .result-panel h2 { font-size: 32px; line-height: 1.1; letter-spacing: -0.055em; }
  .result-panel p { font-size: 15px; line-height: 1.4; }
  .result-panel small { font-size: 13px; }
  .assumptions, .holiday-list { padding: 20px; }
  .assumptions h3, .holiday-list h3 { font-size: 20px; }
  .assumptions li { font-size: 15px; }
  .holiday-list div { display: block; font-size: 15px; }
  .holiday-list strong { display: block; margin-top: 8px; }
  .info-grid { width: min(640px, calc(100% - 28px)); grid-template-columns: 1fr; margin-top: 28px; }
  .info-grid article { padding: 22px; }
  .info-grid h3 { font-size: 20px; }
  .info-grid p { font-size: 16px; }
  footer { width: min(640px, calc(100% - 28px)); flex-direction: column; align-items: flex-start; }
  footer nav { width: 100%; justify-content: space-between; }
  footer button { padding: 10px 0; }
  .static-page { width: min(640px, calc(100% - 28px)); margin-top: 54px; }
  .static-page h1 { font-size: clamp(36px, 10vw, 50px); }
  .content-card { padding: 22px; font-size: 16px; }
  .source-card { width: min(640px, calc(100% - 28px)); padding: 22px; }
  .year-tables, .quick-date-grid, .download-grid { grid-template-columns: 1fr; }
  .embed-preview iframe { height: 930px; }
  .embed-shell { padding: 8px; }
  .embed-shell .calculator-card { width: 100%; }
  .help-overlay {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    padding: 18px;
    background: rgba(16, 28, 46, 0.25);
  }
  .help-sheet {
    width: min(520px, 100%);
    border-radius: 24px;
    border: 1px solid var(--line);
    background: #fff;
    box-shadow: 0 24px 80px rgba(16, 28, 46, 0.28);
    padding: 14px 20px 20px;
  }
  .sheet-handle { width: 44px; height: 5px; border-radius: 999px; background: #cbd8e8; margin: 0 auto 14px; }
  .help-sheet h3 { margin: 0 0 8px; font-size: 20px; }
  .help-sheet p { margin: 0; color: var(--muted); font-size: 16px; line-height: 1.42; }
  .sheet-close {
    width: 100%; height: 52px; margin-top: 18px; border: 0; border-radius: 14px;
    background: var(--navy); color: #fff; font-weight: 900; font-size: 18px;
  }
}

@media (max-width: 390px) {
  .nav-link { font-size: 16px; padding: 10px 15px; }
  .hero h1 { font-size: 42px; }
  .hero p { font-size: 18px; }
  .tab-item { min-height: 46px; }
  .tab-label { font-size: 14px; }
  .field span { font-size: 14px; }
  input, select { font-size: 15px; height: 56px; }
  .holiday-toggle span { font-size: 15px; }
  .result-panel h2 { font-size: 34px; }
  .result-panel p { font-size: 16px; }
}