:root {
  --geo-green: #174c3b;
  --geo-green-dark: #0d352a;
  --geo-green-soft: #2b6a54;
  --geo-mint: #dcece5;
  --geo-ink: #10251e;
  --geo-muted: #4a6158;
  --geo-line: #ccdcd5;
  --geo-panel: #f3f8f5;
  --geo-white: #ffffff;
  --curve-nearest: #a04b39;
  --curve-linear: #2866a7;
  --curve-pchip: #147052;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body.interpolation-page {
  margin: 0;
  color: var(--geo-ink);
  background: var(--geo-white);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
}

.interpolation-page a {
  color: inherit;
}

.interpolation-page .container {
  width: min(1180px, calc(100% - 40px));
  margin-inline: auto;
}

.interpolation-page .skip-link {
  position: fixed;
  z-index: 1000;
  top: 8px;
  left: 8px;
  padding: 10px 14px;
  color: var(--geo-green-dark);
  background: var(--geo-white);
  border-radius: 8px;
  transform: translateY(-160%);
}

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

.interpolation-page .site-header {
  position: sticky;
  z-index: 30;
  top: 0;
  color: var(--geo-white);
  background: var(--geo-green-dark);
  border-bottom: 1px solid rgb(255 255 255 / 18%);
}

.interpolation-page .header-inner {
  min-height: 94px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
}

.interpolation-page .brand {
  display: inline-flex;
  align-items: center;
  min-width: 0;
  text-decoration: none;
}

.interpolation-page .brand-logo {
  display: block;
  width: min(290px, 48vw);
  height: 58px;
  object-fit: contain;
  object-position: left center;
}

.interpolation-page .main-nav ul {
  display: flex;
  align-items: center;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.interpolation-page .main-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 8px 11px;
  border-radius: 999px;
  color: var(--geo-white);
  font-weight: 700;
  text-decoration: none;
}

.interpolation-page .main-nav a:hover,
.interpolation-page .main-nav a:focus-visible,
.interpolation-page .main-nav a[aria-current="page"] {
  background: rgb(255 255 255 / 14%);
}

.interpolation-page .main-nav .lang-link {
  min-width: 42px;
  justify-content: center;
  border: 1px solid rgb(255 255 255 / 30%);
}

.interpolation-page .nav-toggle {
  display: none;
  width: 48px;
  height: 44px;
  padding: 9px;
  border: 1px solid rgb(255 255 255 / 28%);
  border-radius: 9px;
  color: inherit;
  background: transparent;
}

.interpolation-page .nav-toggle > span:not(.visually-hidden) {
  display: block;
  width: 100%;
  height: 2px;
  margin: 5px 0;
  background: currentColor;
}

.interpolation-page .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;
}

.interpolation-intro {
  padding: 72px 0 42px;
  color: var(--geo-white);
  background:
    radial-gradient(circle at 88% 24%, rgb(151 206 179 / 23%), transparent 30%),
    linear-gradient(135deg, var(--geo-green-dark), var(--geo-green-soft));
}

.interpolation-intro-copy {
  max-width: 850px;
}

.interpolation-page .eyebrow {
  margin: 0 0 12px;
  color: #bfe1cf;
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  text-transform: uppercase;
}

.interpolation-intro h1 {
  max-width: 760px;
  margin: 0;
  font-size: clamp(2.25rem, 5.2vw, 4.7rem);
  line-height: 1.02;
  letter-spacing: -0.045em;
}

.interpolation-intro .lead {
  max-width: 760px;
  margin: 25px 0 0;
  color: #edf7f2;
  font-size: clamp(1.05rem, 2vw, 1.28rem);
}

.privacy-note {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 25px 0 0;
  padding: 8px 13px;
  color: var(--geo-green-dark);
  background: #e8f5ee;
  border-radius: 999px;
  font-size: 0.92rem;
  font-weight: 750;
}

.privacy-note::before {
  width: 9px;
  height: 9px;
  background: var(--curve-pchip);
  border-radius: 50%;
  content: "";
}

.interpolation-workspace {
  padding: 58px 0 70px;
}

.workspace-heading {
  max-width: 820px;
  margin-bottom: 30px;
}

.workspace-heading h2,
.method-explanations h2 {
  margin: 0 0 10px;
  color: var(--geo-green-dark);
  font-size: clamp(1.75rem, 3vw, 2.65rem);
  line-height: 1.12;
  letter-spacing: -0.025em;
}

.workspace-heading p,
.method-explanations > p {
  margin: 0;
  color: var(--geo-muted);
}

.interpolation-layout {
  display: grid;
  grid-template-columns: minmax(245px, 0.34fr) minmax(0, 1fr);
  gap: 24px;
  align-items: start;
}

.control-panel,
.chart-panel,
.method-card,
.interpretation-note {
  border: 1px solid var(--geo-line);
  border-radius: 22px;
  background: var(--geo-white);
  box-shadow: 0 16px 38px rgb(15 57 44 / 8%);
}

.control-panel {
  padding: 24px;
}

.control-panel h3,
.chart-panel h3 {
  margin: 0 0 7px;
  color: var(--geo-green-dark);
  font-size: 1.25rem;
  line-height: 1.2;
}

.control-intro,
.drag-hint {
  margin: 0 0 22px;
  color: var(--geo-muted);
  font-size: 0.94rem;
}

.support-controls {
  display: grid;
  gap: 16px;
}

.support-control label {
  display: flex;
  justify-content: space-between;
  gap: 15px;
  margin-bottom: 4px;
  font-size: 0.93rem;
  font-weight: 750;
}

.support-control output {
  min-width: 2.5ch;
  color: var(--geo-green-soft);
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.support-control input[type="range"] {
  width: 100%;
  accent-color: var(--geo-green-soft);
  cursor: ns-resize;
}

.method-select {
  display: grid;
  gap: 10px;
  margin: 26px 0 0;
  padding: 20px 0 0;
  border: 0;
  border-top: 1px solid var(--geo-line);
}

.method-select legend {
  float: left;
  width: 100%;
  margin: 0 0 10px;
  padding: 0;
  color: var(--geo-green-dark);
  font-weight: 800;
}

.method-select label {
  display: flex;
  align-items: center;
  gap: 9px;
  min-height: 36px;
  cursor: pointer;
}

.method-select input {
  width: 18px;
  height: 18px;
  margin: 0;
  accent-color: var(--geo-green-soft);
}

.method-swatch {
  width: 28px;
  height: 4px;
  border-radius: 4px;
}

.method-swatch.nearest {
  background: var(--curve-nearest);
}

.method-swatch.linear {
  background: var(--curve-linear);
}

.method-swatch.pchip {
  background: var(--curve-pchip);
}

.realization-control {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 10px;
  min-width: 0;
}

.realization-control label {
  flex: 1 1 auto;
  min-width: 0;
  gap: 8px;
}

.method-select input[type="number"] {
  flex: 0 0 70px;
  width: 70px;
  height: 44px;
  padding: 6px 8px;
  border: 1px solid var(--geo-line);
  border-radius: 8px;
  color: var(--geo-ink);
  background: var(--geo-white);
  font: inherit;
}

.realization-help {
  margin: -2px 0 0;
  color: var(--geo-muted);
  font-size: 0.88rem;
  line-height: 1.45;
}

.method-swatch.realizations {
  height: 1px;
  border-radius: 0;
  background: #000;
}

.curve.curve-realization {
  fill: none;
  stroke: #000;
  stroke-width: 1;
  vector-effect: non-scaling-stroke;
  pointer-events: none;
}
.reset-button {
  width: 100%;
  min-height: 46px;
  margin-top: 24px;
  padding: 10px 16px;
  border: 1px solid var(--geo-green-soft);
  border-radius: 999px;
  color: var(--geo-green-dark);
  background: var(--geo-white);
  font: inherit;
  font-weight: 800;
  cursor: pointer;
}

.reset-button:hover,
.reset-button:focus-visible {
  color: var(--geo-white);
  background: var(--geo-green-soft);
}

.chart-panel {
  min-width: 0;
  padding: 24px;
  background: var(--geo-panel);
}

.chart-frame {
  overflow: hidden;
  border: 1px solid var(--geo-line);
  border-radius: 16px;
  background: var(--geo-white);
}

#interpolation-chart {
  display: block;
  width: 100%;
  height: auto;
  min-height: 310px;
  touch-action: none;
}

#chart-grid line {
  stroke: #e2ebe6;
  stroke-width: 1;
}

.axis-line {
  stroke: #667a71;
  stroke-width: 1.4;
}

.axis-tick {
  fill: #5b6d65;
  font-size: 12px;
}

.axis-title {
  fill: var(--geo-green-dark);
  font-size: 14px;
  font-weight: 750;
}

.curve {
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 4;
  vector-effect: non-scaling-stroke;
}

.curve-nearest {
  stroke: var(--curve-nearest);
  stroke-dasharray: 9 7;
}

.curve-linear {
  stroke: var(--curve-linear);
}

.curve-pchip {
  stroke: var(--curve-pchip);
}

.curve.is-hidden {
  display: none;
}

.support-point {
  fill: var(--geo-white);
  stroke: var(--geo-green-dark);
  stroke-width: 4;
  cursor: ns-resize;
  vector-effect: non-scaling-stroke;
}

.support-point:hover {
  fill: var(--geo-mint);
}

.chart-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
  margin: 17px 0 0;
  padding: 0;
  list-style: none;
  color: var(--geo-muted);
  font-size: 0.9rem;
}

.chart-legend li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.method-explanations {
  padding: 0 0 78px;
}

.method-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 27px;
}

.method-card {
  padding: 24px;
}

.method-card::before {
  display: block;
  width: 42px;
  height: 5px;
  margin-bottom: 18px;
  border-radius: 5px;
  background: var(--card-accent);
  content: "";
}

.method-card.nearest-card {
  --card-accent: var(--curve-nearest);
}

.method-card.linear-card {
  --card-accent: var(--curve-linear);
}

.method-card.pchip-card {
  --card-accent: var(--curve-pchip);
}

.method-card h3 {
  margin: 0 0 10px;
  color: var(--geo-green-dark);
  font-size: 1.2rem;
}

.method-card p {
  margin: 0;
  color: var(--geo-muted);
}

.interpretation-note {
  margin-top: 22px;
  padding: 24px;
  border-left: 6px solid var(--geo-green-soft);
  background: var(--geo-panel);
}

.interpretation-note h3 {
  margin: 0 0 8px;
  color: var(--geo-green-dark);
}

.interpretation-note p {
  margin: 0;
  color: var(--geo-muted);
}

.interpolation-page .site-footer {
  padding: 30px 0;
  color: #eaf4ef;
  background: var(--geo-green-dark);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.footer-inner p {
  margin: 0;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
}

.footer-links a {
  color: inherit;
}

.release-note {
  color: #bcd4c8;
  font-size: 0.82rem;
}

.interpolation-page :focus-visible {
  outline: 3px solid #a7d8bd;
  outline-offset: 3px;
}

@media (max-width: 75em) {
  .interpolation-page .nav-toggle {
    display: block;
  }

  .interpolation-page .main-nav {
    position: absolute;
    top: 100%;
    right: 20px;
    left: 20px;
    display: none;
    padding: 12px;
    background: var(--geo-green-dark);
    border: 1px solid rgb(255 255 255 / 22%);
    border-radius: 15px;
    box-shadow: 0 18px 42px rgb(0 0 0 / 22%);
  }

  .interpolation-page .main-nav.open {
    display: block;
  }

  .interpolation-page .main-nav ul {
    align-items: stretch;
    flex-direction: column;
  }

  .interpolation-page .main-nav a {
    width: 100%;
  }

}

@media (max-width: 900px) {
  .interpolation-layout {
    grid-template-columns: 1fr;
  }

  .support-controls {
    grid-template-columns: repeat(2, 1fr);
  }

  .method-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .interpolation-page .container {
    width: min(100% - 24px, 1180px);
  }

  .interpolation-page .header-inner {
    min-height: 76px;
    gap: 12px;
  }

  .interpolation-page .brand-logo {
    width: min(235px, 66vw);
    height: 48px;
  }

  .interpolation-intro {
    padding: 48px 0 34px;
  }

  .interpolation-workspace {
    padding: 42px 0 55px;
  }

  .control-panel,
  .chart-panel,
  .method-card,
  .interpretation-note {
    border-radius: 16px;
  }

  .support-controls {
    grid-template-columns: 1fr;
  }

  .chart-panel {
    padding: 14px;
  }

  .drag-hint {
    margin-bottom: 12px;
  }

  #interpolation-chart {
    min-height: 260px;
  }

  .footer-inner {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}
/* Link to the advanced comparison, release 2026-10-04-2. */
.full-tool-link{margin:1.1rem 0 0;line-height:1.5;}
.full-tool-link a{display:inline-block;padding:.45rem .8rem;border-radius:999px;background:#fff;color:#0a2a22;font-weight:760;text-decoration:none;}
.full-tool-link a:hover,.full-tool-link a:focus-visible{background:#e3f3eb;text-decoration:underline;}