:root {
  --bg: #fafaf9;
  --bg-alt: #f4f4f2;
  --paper: #ffffff;
  --ink: #18181b;
  --ink-soft: #3f3f46;
  --ink-mute: #71717a;
  --ink-faint: #a1a1aa;
  --rule: #d4d4d8;
  --rule-soft: #e4e4e7;
  --sans: 'IBM Plex Sans', -apple-system, system-ui, sans-serif;
  --mono: 'IBM Plex Mono', ui-monospace, 'SF Mono', Menlo, monospace;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink);
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-feature-settings: "ss01", "cv10";
}

.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;
}

/* ============ HEADER ============ */
header.site {
  border-bottom: 1px solid var(--rule);
  background: #ffefca;
  position: sticky;
  top: 0;
  z-index: 10;
}
.nav {
  max-width: 960px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}
.brand {
  font-family: var(--mono);
  font-weight: 500;
  font-size: 14px;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: -0.01em;
}
.nav-meta {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--ink-mute);
  letter-spacing: 0.05em;
}

/* ============ MAIN CONTAINER ============ */
main {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

main > section {
  padding: 56px 0;
  border-bottom: 1px solid var(--rule-soft);
}
main > section:last-child { border-bottom: none; }
.intro-section { padding: 64px 0 32px; border-bottom: none; }
.calc-section { padding-top: 24px; border-bottom: 1px solid var(--rule); }

@media (max-width: 700px) {
  main > section { padding: 44px 0; }
  .intro-section { padding: 48px 0 24px; }
  .nav { padding: 14px 20px; }
  main { padding: 0 20px; }
}

h1, h2, h3 {
  font-family: var(--sans);
  font-weight: 500;
  letter-spacing: -0.02em;
  color: var(--ink);
}

h1 {
  font-size: clamp(32px, 5vw, 52px);
  line-height: 1.05;
  margin-bottom: 20px;
  font-weight: 600;
  letter-spacing: -0.03em;
}

h2 {
  font-size: clamp(22px, 3vw, 28px);
  line-height: 1.2;
  margin-bottom: 14px;
  font-weight: 600;
}

h3 {
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.01em;
  margin-bottom: 12px;
}

.eyebrow {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-mute);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 20px;
}

.lede {
  font-size: clamp(17px, 2vw, 19px);
  line-height: 1.55;
  color: var(--ink-soft);
  max-width: 680px;
  font-weight: 400;
}

.section-intro {
  color: var(--ink-soft);
  margin-bottom: 28px;
  max-width: 680px;
}

/* ============ CALCULATOR ============ */
.calc {
  padding: 32px;
  background: var(--paper);
  border: 1px solid var(--ink);
}
@media (max-width: 600px) {
  .calc { padding: 24px 20px; }
}

.calc-row {
  margin-bottom: 20px;
}
.calc-row:last-child { margin-bottom: 0; }

.calc-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-bottom: 24px;
}
@media (max-width: 600px) {
  .calc-grid { grid-template-columns: 1fr; gap: 20px; }
}

.field-label {
  display: block;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 10px;
}

.field-hint {
  font-size: 12px;
  color: var(--ink-mute);
  margin-top: 6px;
  line-height: 1.4;
}

input[type="date"] {
  width: 100%;
  padding: 12px 14px;
  font-family: var(--mono);
  font-size: 15px;
  color: var(--ink);
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 0;
  -webkit-appearance: none;
  appearance: none;
  font-variant-numeric: tabular-nums;
  transition: border-color 0.15s;
}
input[type="date"]:focus {
  outline: none;
  border-color: var(--ink);
}

.select-input {
  width: 100%;
  padding: 12px 40px 12px 14px;
  font-family: var(--mono);
  font-size: 15px;
  color: var(--ink);
  background: var(--bg);
  border: 1px solid var(--rule);
  border-radius: 0;
  -webkit-appearance: none;
  appearance: none;
  font-variant-numeric: tabular-nums;
  transition: border-color 0.15s;
  cursor: pointer;
  background-image: linear-gradient(45deg, transparent 50%, var(--ink) 50%), linear-gradient(135deg, var(--ink) 50%, transparent 50%);
  background-position: calc(100% - 18px) 50%, calc(100% - 12px) 50%;
  background-size: 6px 6px, 6px 6px;
  background-repeat: no-repeat;
}
.select-input:focus {
  outline: none;
  border-color: var(--ink);
}

/* Progressive field reveal */
.calc-fields[hidden] {
  display: none !important;
}
.calc-fields[data-fields="essai"] {
  margin-bottom: 24px;
}

/* Radio group */
.radio-group {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
}
@media (max-width: 500px) {
  .radio-group { grid-template-columns: 1fr; }
}

.radio {
  background: var(--paper);
  cursor: pointer;
  transition: background 0.15s;
  position: relative;
}
.radio input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}
.radio-visual {
  display: block;
  padding: 16px 18px;
  font-size: 15px;
  font-weight: 500;
  color: var(--ink);
  line-height: 1.3;
}
.radio-sub {
  display: block;
  font-size: 12px;
  color: var(--ink-mute);
  font-weight: 400;
  margin-top: 2px;
  letter-spacing: 0.01em;
}
.radio:hover {
  background: var(--bg-alt);
}
.radio input:checked ~ .radio-visual {
  background: var(--ink);
  color: var(--bg);
}
.radio input:checked ~ .radio-visual .radio-sub {
  color: var(--ink-faint);
}
.radio input:focus-visible ~ .radio-visual {
  outline: 2px solid var(--ink);
  outline-offset: -2px;
}

/* Submit button */
.btn-calc {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  padding: 16px 28px;
  font-family: var(--sans);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--bg);
  background: var(--ink);
  border: none;
  cursor: pointer;
  transition: background 0.15s;
}
.btn-calc:hover { background: #000; }
.btn-calc:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }

/* ============ RESULTS ============ */
.results {
  margin-top: 32px;
  padding: 28px;
  background: var(--paper);
  border: 1px solid var(--rule);
  animation: fadeIn 300ms ease;
}
@media (max-width: 600px) {
  .results { padding: 20px 16px; }
}
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}

.results-top {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--rule);
  border: 1px solid var(--rule);
  margin-bottom: 28px;
}
@media (max-width: 600px) {
  .results-top { grid-template-columns: 1fr; }
}

.result-block {
  background: var(--paper);
  padding: 20px;
}
.result-block-hero {
  background: var(--ink);
}

.result-label {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 8px;
}
.result-block-hero .result-label { color: var(--ink-faint); }

.result-value {
  font-family: var(--sans);
  font-size: 28px;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--ink);
  line-height: 1.1;
  margin-bottom: 4px;
  font-variant-numeric: tabular-nums;
}
.result-block-hero .result-value { color: var(--bg); font-size: 32px; }

.result-sub {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-mute);
  font-variant-numeric: tabular-nums;
}
.result-block-hero .result-sub { color: var(--ink-faint); }

/* Timeline */
.timeline {
  display: grid;
  gap: 0;
  margin-bottom: 24px;
  position: relative;
}
.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: var(--rule);
}
.timeline-row {
  display: grid;
  grid-template-columns: 30px 1fr;
  gap: 16px;
  padding: 12px 0;
  align-items: start;
  position: relative;
}
.timeline-dot {
  width: 14px;
  height: 14px;
  border: 2px solid var(--ink);
  border-radius: 50%;
  background: var(--paper);
  margin-top: 4px;
  z-index: 1;
  position: relative;
}
.timeline-dot-end {
  background: var(--ink);
}
.timeline-label {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
  margin-bottom: 4px;
}
.timeline-date {
  font-family: var(--sans);
  font-size: 17px;
  font-weight: 500;
  color: var(--ink);
  letter-spacing: -0.005em;
  font-variant-numeric: tabular-nums;
}
.timeline-note {
  font-size: 12px;
  color: var(--ink-mute);
  margin-top: 4px;
  font-style: italic;
}

.results-note {
  padding-top: 20px;
  border-top: 1px solid var(--rule-soft);
  font-size: 13px;
  color: var(--ink-mute);
  line-height: 1.55;
}

/* Warning banner (essai overrun) */
.warning {
  display: flex;
  gap: 16px;
  padding: 18px 20px;
  background: var(--ink);
  color: var(--bg);
  margin-bottom: 24px;
  align-items: flex-start;
}
.warning[hidden] { display: none; }
.warning-icon {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
  border: 2px solid var(--bg);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 16px;
  line-height: 1;
}
.warning-title {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 15px;
  margin-bottom: 4px;
  letter-spacing: -0.005em;
}
.warning-content p {
  font-size: 13px;
  color: var(--ink-faint);
  line-height: 1.5;
  margin: 0;
}

.cell-note {
  font-family: var(--sans);
  font-size: 11px;
  color: var(--ink-mute);
  font-weight: 400;
  letter-spacing: 0.02em;
  margin-left: 4px;
}

/* Error */
.results[data-error="true"] {
  border-color: var(--ink);
}
.results-error {
  display: none;
  padding: 16px;
  background: var(--bg-alt);
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 16px;
}
.results[data-error="true"] .results-error {
  display: block;
}

/* ============ RULES TABLE ============ */
.rules-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 36px;
  font-variant-numeric: tabular-nums;
}
.rules-table thead {
  border-bottom: 1px solid var(--ink);
}
.rules-table th {
  text-align: left;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
  padding: 10px 16px 10px 0;
}
.rules-table th:not(:first-child) { text-align: right; padding-right: 0; }
.rules-table td {
  padding: 16px 16px 16px 0;
  border-bottom: 1px solid var(--rule-soft);
  font-size: 15px;
  color: var(--ink-soft);
}
.rules-table td:not(:first-child) {
  text-align: right;
  padding-right: 0;
  font-family: var(--mono);
}
.rules-table td strong {
  color: var(--ink);
  font-weight: 600;
}
.rules-table tr:last-child td { border-bottom: none; }

.rules-sub {
  margin-top: 20px;
  margin-bottom: 16px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-mute);
  font-weight: 500;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 10px;
}

.rule-box {
  border: 1px solid var(--rule);
  background: var(--paper);
}
.rule-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 20px;
  padding: 16px 20px;
  align-items: center;
  border-bottom: 1px solid var(--rule-soft);
  font-size: 14px;
  color: var(--ink-soft);
}
.rule-row:last-child { border-bottom: none; }
.rule-row strong {
  color: var(--ink);
  font-weight: 600;
}
.rule-arrow {
  font-family: var(--mono);
  font-size: 16px;
  color: var(--ink-faint);
}
@media (max-width: 600px) {
  .rule-row {
    grid-template-columns: 1fr;
    gap: 4px;
    padding: 14px 16px;
  }
  .rule-arrow { display: none; }
}

.rules-foot {
  margin-top: 14px;
  font-size: 12px;
  color: var(--ink-mute);
  line-height: 1.5;
}

/* ============ LIMITS ============ */
.limits-list {
  list-style: none;
  padding: 0;
  display: grid;
  gap: 14px;
}
.limits-list li {
  padding: 16px 20px;
  background: var(--paper);
  border: 1px solid var(--rule-soft);
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.55;
}
.limits-list li strong {
  display: block;
  font-family: var(--sans);
  font-weight: 600;
  color: var(--ink);
  font-size: 15px;
  margin-bottom: 4px;
  letter-spacing: -0.005em;
}

/* ============ FAQ ============ */
.faq details {
  border-bottom: 1px solid var(--rule-soft);
  padding: 18px 0;
}
.faq details:first-child { border-top: 1px solid var(--rule); }
.faq details:last-child { border-bottom: 1px solid var(--rule); }
.faq summary {
  font-weight: 500;
  font-size: 15px;
  color: var(--ink);
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 24px;
  letter-spacing: -0.005em;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: '+';
  font-family: var(--mono);
  font-weight: 400;
  font-size: 20px;
  color: var(--ink-mute);
  line-height: 0.7;
  flex-shrink: 0;
  transition: transform 0.15s;
}
.faq details[open] summary::after {
  content: '−';
  color: var(--ink);
}
.faq details p {
  margin-top: 14px;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.6;
  max-width: 720px;
}

/* ============ FOOTER ============ */
footer {
  border-top: 1px solid var(--ink);
  background: var(--bg);
  margin-top: 40px;
  padding: 40px 24px;
}
.foot {
  max-width: 960px;
  margin: 0 auto;
}
.foot-main {
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.6;
  margin-bottom: 24px;
  max-width: 680px;
}
.foot-main a {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--ink);
  font-weight: 500;
}
.foot-main a:hover {
  color: var(--ink-soft);
  border-bottom-color: var(--ink-soft);
}
.foot-meta {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.05em;
  color: var(--ink-mute);
  padding-top: 24px;
  border-top: 1px solid var(--rule-soft);
}
.foot-legal {
  margin-top: 16px;
  font-size: 12px;
  color: var(--ink-mute);
  line-height: 1.55;
  font-style: italic;
  max-width: 720px;
}

/* ============ LINKS ============ */
a {
  color: var(--ink);
}