:root {
  --paper: #f3f0e8;
  --paper-deep: #e9e4d8;
  --ink: #182019;
  --muted: #60675f;
  --line: #cec8ba;
  --accent: #a83f28;
  --accent-dark: #7c2d1d;
  --result: #17201a;
  --result-muted: #bac2b7;
  --result-line: #38423a;
  --focus: #1262a3;
  --radius: 18px;
  --shadow: 0 24px 70px rgba(40, 39, 31, 0.10);
}

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

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-width: 280px;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.55;
  text-rendering: optimizeLegibility;
  padding-bottom: env(safe-area-inset-bottom, 0);
}

button,
input {
  font: inherit;
}

button,
label,
summary {
  -webkit-tap-highlight-color: transparent;
}

a {
  color: inherit;
}

.page-width {
  width: min(1120px, calc(100% - 40px));
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--ink);
  color: #fff;
  transform: translateY(-160%);
}

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

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

.site-header {
  border-bottom: 1px solid var(--line);
}

.header-inner {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.wordmark {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-size: 14px;
  font-weight: 750;
  letter-spacing: -0.01em;
  text-decoration: none;
}

.wordmark-mark {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  border-radius: 50%;
  background: var(--ink);
  color: var(--paper);
  font-size: 19px;
  line-height: 1;
}

.utility-label,
.step-label,
.eyebrow,
.formula-index {
  margin: 0;
  color: var(--muted);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.12em;
  line-height: 1.3;
  text-transform: uppercase;
}

.hero {
  padding-top: clamp(58px, 9vw, 112px);
  padding-bottom: clamp(34px, 5vw, 58px);
}

.eyebrow {
  color: var(--accent-dark);
}

.hero h1,
.method h2,
.explanation h2,
.faq h2 {
  margin: 16px 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 500;
  letter-spacing: -0.045em;
  line-height: 0.99;
}

.hero h1 {
  max-width: 900px;
  font-size: clamp(43px, 7vw, 82px);
}

.hero-copy {
  max-width: 670px;
  margin: 27px 0 0;
  color: var(--muted);
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.55;
}

.calculator-section {
  scroll-margin-top: 18px;
}

.tool-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.calculator-form,
.result-panel {
  min-width: 0;
  padding: clamp(25px, 4vw, 48px);
}

.calculator-form {
  background: #fbf9f3;
}

.panel-heading h2 {
  margin: 7px 0 0;
  font-size: clamp(24px, 3vw, 32px);
  letter-spacing: -0.035em;
  line-height: 1.15;
}

.change-fieldset {
  min-width: 0;
  margin: 32px 0 0;
  padding: 0;
  border: 0;
}

.change-fieldset legend,
.field-group > label {
  display: block;
  margin-bottom: 9px;
  color: var(--ink);
  font-size: 14px;
  font-weight: 700;
}

.segment-control {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--paper);
}

.segment-control input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.segment-control label {
  display: grid;
  min-height: 48px;
  place-items: center;
  padding: 8px 12px;
  border-radius: 8px;
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
  font-weight: 700;
  text-align: center;
  transition: background-color 140ms ease, color 140ms ease, box-shadow 140ms ease;
}

.segment-control input:checked + label {
  background: #fff;
  color: var(--ink);
  box-shadow: 0 3px 12px rgba(36, 34, 26, 0.10);
}

.segment-control input:focus-visible + label {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.field-group {
  margin-top: 25px;
}

.field-group input {
  width: 100%;
  min-height: 56px;
  padding: 12px 14px;
  border: 1px solid #aaa597;
  border-radius: 10px;
  outline: none;
  background: #fff;
  color: var(--ink);
  font-size: 18px;
  font-variant-numeric: tabular-nums;
  transition: border-color 140ms ease, box-shadow 140ms ease;
}

.field-group input:focus {
  border-color: var(--focus);
  box-shadow: 0 0 0 3px rgba(18, 98, 163, 0.18);
}

.field-group input[aria-invalid="true"] {
  border-color: #a72d22;
  box-shadow: 0 0 0 3px rgba(167, 45, 34, 0.12);
}

.input-with-suffix {
  position: relative;
}

.input-with-suffix input {
  padding-right: 48px;
}

.input-with-suffix > span {
  position: absolute;
  top: 50%;
  right: 17px;
  color: var(--muted);
  font-weight: 700;
  transform: translateY(-50%);
}

.field-hint,
.field-error,
.form-status {
  min-height: 19px;
  margin: 6px 0 0;
  font-size: 12px;
}

.field-hint {
  color: var(--muted);
}

.field-error,
.form-status.error {
  color: #8e251d;
  font-weight: 650;
}

.form-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 28px;
}

.button,
.copy-link {
  min-height: 48px;
  border-radius: 10px;
  cursor: pointer;
  font-size: 14px;
  font-weight: 750;
}

.button {
  border: 1px solid transparent;
  padding: 11px 17px;
}

.button-primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 8px 18px rgba(126, 41, 24, 0.18);
}

.button-primary:hover {
  background: var(--accent-dark);
}

.button-quiet {
  border-color: var(--line);
  background: transparent;
  color: var(--muted);
}

.button-quiet:hover {
  background: var(--paper);
  color: var(--ink);
}

.button:focus-visible,
.copy-link:focus-visible,
summary:focus-visible,
a:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}

.form-status {
  margin-top: 10px;
}

.result-panel {
  display: flex;
  flex-direction: column;
  background: var(--result);
  color: #f7f4ec;
  outline: none;
}

.result-panel:focus-visible {
  box-shadow: inset 0 0 0 3px #7ab8ea;
}

.result-topline {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}

.step-label-light {
  color: var(--result-muted);
}

.copy-link {
  min-width: 88px;
  padding: 8px 13px;
  border: 1px solid var(--result-line);
  background: transparent;
  color: #f7f4ec;
}

.copy-link:hover:not(:disabled) {
  border-color: #aab5aa;
  background: rgba(255, 255, 255, 0.06);
}

.copy-link:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.primary-result {
  display: block;
  margin-top: clamp(36px, 7vw, 78px);
  color: #fffaf0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(62px, 9vw, 105px);
  font-variant-numeric: lining-nums tabular-nums;
  font-weight: 500;
  letter-spacing: -0.065em;
  line-height: 0.9;
  overflow-wrap: anywhere;
}

.primary-result[data-size="long"] {
  font-size: clamp(43px, 7vw, 76px);
}

.primary-result[data-size="xlong"] {
  font-size: clamp(33px, 5.5vw, 58px);
}

.result-summary {
  max-width: 480px;
  margin: 22px 0 0;
  color: var(--result-muted);
  font-size: 16px;
}

.result-details {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  margin: auto 0 0;
  padding-top: clamp(42px, 8vw, 88px);
}

.result-details > div {
  min-width: 0;
  padding: 15px 12px 0 0;
  border-top: 1px solid var(--result-line);
}

.result-details > div + div {
  padding-left: 15px;
  border-left: 1px solid var(--result-line);
}

.result-details dt {
  color: var(--result-muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.result-details dd {
  margin: 7px 0 0;
  font-size: 16px;
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  overflow-wrap: anywhere;
}

.check-strip {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 15px;
  margin-top: 28px;
  padding: 15px 16px;
  border: 1px solid var(--result-line);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.035);
  color: var(--result-muted);
  font-size: 13px;
}

.check-strip output {
  color: #f7f4ec;
  font-variant-numeric: tabular-nums;
  text-align: right;
  overflow-wrap: anywhere;
}

.copy-status {
  min-height: 20px;
  margin: 9px 0 -20px;
  color: var(--result-muted);
  font-size: 12px;
  text-align: right;
}

.local-note {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 14px 3px 0;
  color: var(--muted);
  font-size: 12px;
}

.local-note span {
  color: #3e7c4c;
  font-size: 8px;
}

.ad-slot {
  margin-top: clamp(52px, 8vw, 92px);
}

.ad-slot-inner {
  display: grid;
  min-height: 112px;
  place-items: center;
  border: 1px dashed #c7c1b4;
  color: #8a8a82;
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.method {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: clamp(40px, 8vw, 105px);
  padding-top: clamp(85px, 13vw, 160px);
}

.method h2,
.explanation h2,
.faq h2 {
  font-size: clamp(37px, 5vw, 59px);
}

.method-intro > p:last-child {
  max-width: 470px;
  margin: 26px 0 0;
  color: var(--muted);
  font-size: 17px;
}

.formula-list {
  border-top: 1px solid var(--ink);
}

.formula-card {
  padding: 30px 0 32px;
  border-bottom: 1px solid var(--line);
}

.formula-card h3 {
  margin: 9px 0 0;
  font-size: 23px;
  letter-spacing: -0.025em;
}

.formula-card .formula {
  margin: 17px 0 0;
  color: var(--accent-dark);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: clamp(14px, 2vw, 17px);
  font-weight: 700;
  overflow-wrap: anywhere;
}

.formula-card > p:last-child {
  margin: 14px 0 0;
  color: var(--muted);
}

.explanation {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(45px, 9vw, 120px);
  margin-top: clamp(100px, 14vw, 175px);
  padding-top: 28px;
  border-top: 1px solid var(--ink);
}

.explanation-copy {
  padding-top: 7px;
  color: var(--muted);
  font-size: 17px;
}

.explanation-copy p {
  margin: 0 0 20px;
}

.faq {
  max-width: 820px;
  margin-top: clamp(100px, 14vw, 170px);
}

.faq-list {
  margin-top: 35px;
  border-top: 1px solid var(--ink);
}

.faq details {
  border-bottom: 1px solid var(--line);
}

.faq summary {
  position: relative;
  min-height: 66px;
  padding: 20px 45px 20px 0;
  cursor: pointer;
  font-size: 17px;
  font-weight: 720;
  list-style: none;
}

.faq summary::-webkit-details-marker {
  display: none;
}

.faq summary::after {
  content: "+";
  position: absolute;
  top: 50%;
  right: 7px;
  font-size: 25px;
  font-weight: 400;
  transform: translateY(-50%);
}

.faq details[open] summary::after {
  content: "−";
}

.faq details p {
  max-width: 690px;
  margin: -4px 0 24px;
  color: var(--muted);
}

.ad-slot-secondary {
  margin-top: clamp(85px, 12vw, 145px);
}

.site-footer {
  margin-top: clamp(70px, 10vw, 115px);
  border-top: 1px solid var(--line);
}

.footer-inner {
  display: flex;
  min-height: 105px;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  color: var(--muted);
  font-size: 13px;
}

.footer-inner a {
  color: var(--ink);
  font-weight: 700;
  text-underline-offset: 3px;
}

.noscript-message {
  position: fixed;
  z-index: 20;
  right: 16px;
  bottom: 16px;
  left: 16px;
  margin: 0;
  padding: 12px 15px;
  border-radius: 10px;
  background: #fff1c6;
  color: #4c3c16;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.16);
  font-size: 14px;
  text-align: center;
}

.error-page {
  display: grid;
  min-height: 100dvh;
  place-items: center;
  padding: 40px 20px;
}

.error-content {
  max-width: 650px;
  text-align: center;
}

.error-code {
  margin: 0;
  color: var(--accent-dark);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.16em;
}

.error-content h1 {
  margin: 16px 0 0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(48px, 10vw, 82px);
  font-weight: 500;
  letter-spacing: -0.05em;
  line-height: 1;
}

.error-content p:not(.error-code) {
  margin: 24px auto 0;
  color: var(--muted);
  font-size: 18px;
}

.error-content .button {
  display: inline-grid;
  margin-top: 30px;
  place-items: center;
  text-decoration: none;
}

@media (max-width: 800px) {
  .tool-grid,
  .method,
  .explanation {
    grid-template-columns: 1fr;
  }

  .method,
  .explanation {
    gap: 46px;
  }

  .result-panel {
    min-height: 520px;
  }

  .method-intro > p:last-child {
    max-width: 620px;
  }
}

@media (max-width: 520px) {
  .page-width {
    width: min(100% - 28px, 1120px);
  }

  .header-inner {
    min-height: 64px;
  }

  .utility-label {
    display: none;
  }

  .hero {
    padding-top: 52px;
  }

  .hero h1 {
    font-size: clamp(40px, 13vw, 58px);
  }

  .calculator-form,
  .result-panel {
    padding: 25px 20px 28px;
  }

  .form-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .result-panel {
    min-height: 500px;
  }

  .primary-result {
    margin-top: 50px;
  }

  .result-details {
    grid-template-columns: 1fr;
    padding-top: 55px;
  }

  .result-details > div,
  .result-details > div + div {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    align-items: baseline;
    gap: 12px;
    padding: 12px 0;
    border-top: 1px solid var(--result-line);
    border-left: 0;
  }

  .result-details dd {
    margin-top: 0;
    text-align: right;
  }

  .check-strip {
    grid-template-columns: 1fr;
    gap: 7px;
    margin-top: 20px;
  }

  .check-strip output {
    text-align: left;
  }

  .copy-status {
    margin-bottom: -15px;
  }

  .ad-slot-inner {
    min-height: 100px;
  }

  .method h2,
  .explanation h2,
  .faq h2 {
    font-size: clamp(36px, 11vw, 48px);
  }

  .footer-inner {
    align-items: flex-start;
    flex-direction: column;
    justify-content: center;
    gap: 3px;
    padding-block: 28px;
  }

  .footer-inner p {
    margin: 0;
  }
}

@media (max-width: 350px) {
  .page-width {
    width: calc(100% - 20px);
  }

  .segment-control label {
    padding-inline: 6px;
    font-size: 12px;
  }

  .calculator-form,
  .result-panel {
    padding-inline: 16px;
  }

  .copy-link {
    min-width: 80px;
    padding-inline: 10px;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}

@media print {
  .site-header,
  .form-actions,
  .copy-link,
  .copy-status,
  .local-note,
  .ad-slot,
  .site-footer {
    display: none !important;
  }

  body {
    background: #fff;
  }

  .hero {
    padding-top: 20px;
  }

  .tool-grid {
    box-shadow: none;
  }
}