:root {
  --ink: #102a43;
  --ink-deep: #091a28;
  --paper: #f6f1e8;
  --paper-light: #fffdf8;
  --paper-dark: #e7dfd1;
  --cobalt: #2161f5;
  --cobalt-deep: #1746b4;
  --yellow: #f3c969;
  --red: #d4503f;
  --slate: #50627a;
  --line: #c8c0b4;
  --display: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --body: "Avenir Next", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", "Courier New", monospace;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--paper);
  color: var(--ink);
  scroll-behavior: smooth;
}

body {
  margin: 0;
  max-width: 100%;
  overflow-x: hidden;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body);
  font-size: 16px;
  line-height: 1.58;
  text-rendering: optimizeLegibility;
}

img,
svg {
  display: block;
  max-width: 100%;
}

a {
  color: inherit;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
label:focus-within {
  outline: 3px solid var(--yellow);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  z-index: 20;
  top: 0.75rem;
  left: 0.75rem;
  transform: translateY(-180%);
  padding: 0.7rem 1rem;
  min-height: 44px;
  background: var(--yellow);
  color: var(--ink-deep);
  font-weight: 800;
  text-decoration: none;
}

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

.masthead {
  position: relative;
  overflow: hidden;
  background: var(--ink);
  color: var(--paper-light);
}

.masthead::after {
  position: absolute;
  right: -8vw;
  bottom: -18rem;
  width: 42rem;
  height: 42rem;
  border: 1px solid rgba(243, 201, 105, 0.24);
  border-radius: 50%;
  box-shadow: 0 0 0 3rem rgba(243, 201, 105, 0.06), 0 0 0 6rem rgba(243, 201, 105, 0.04);
  content: "";
  pointer-events: none;
}

.topbar,
.hero,
.section,
.site-footer {
  width: min(1240px, calc(100% - 3rem));
  margin-right: auto;
  margin-left: auto;
}

.topbar {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 4.5rem;
  border-bottom: 1px solid rgba(246, 241, 232, 0.26);
}

.brand {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  line-height: 1.2;
  text-decoration: none;
}

.brand span {
  color: var(--yellow);
}

.language-switch {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
}

.language-switch a {
  display: inline-flex;
  min-height: 44px;
  min-width: 44px;
  align-items: center;
  justify-content: center;
  padding: 0.8rem 0.1rem;
  text-decoration: none;
}

.language-switch a:hover,
.language-switch .is-current {
  color: var(--yellow);
}

.language-switch .is-current {
  border-bottom: 2px solid var(--yellow);
}

.hero {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(20rem, 0.78fr);
  gap: clamp(2rem, 6vw, 7rem);
  align-items: end;
  padding-top: clamp(4rem, 6vw, 6rem);
  padding-bottom: clamp(4rem, 7vw, 6.5rem);
}

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

.eyebrow,
.section-kicker,
.answer-label,
.boundary-card-kicker,
.source-card-kicker,
.live-label,
.next-question span,
.fence-number,
.ledger-tag {
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.13em;
  line-height: 1.35;
  text-transform: uppercase;
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  margin: 0 0 1.2rem;
  color: var(--yellow);
}

.eyebrow-mark {
  width: 2.5rem;
  height: 0.45rem;
  border-top: 2px solid var(--yellow);
  border-bottom: 2px solid var(--red);
}

h1,
h2,
h3,
p {
  max-width: 70ch;
}

h1,
h2,
h3 {
  margin-top: 0;
  font-family: var(--display);
  font-weight: 700;
  letter-spacing: -0.045em;
}

h1 {
  max-width: 12ch;
  margin-bottom: 1.6rem;
  color: var(--paper-light);
  font-size: clamp(3.5rem, 6vw, 6.4rem);
  line-height: 0.91;
}

.deck {
  max-width: 48rem;
  margin: 0;
  color: rgba(255, 253, 248, 0.87);
  font-size: clamp(1.02rem, 1.5vw, 1.25rem);
  line-height: 1.55;
}

.answer-strip {
  max-width: 42rem;
  margin-top: 2rem;
  padding: 1.15rem 1.3rem 1.2rem;
  border-left: 0.5rem solid var(--red);
  background: var(--yellow);
  color: var(--ink-deep);
}

.answer-strip p {
  margin: 0.35rem 0 0;
  font-size: 1.02rem;
  font-weight: 650;
  line-height: 1.4;
}

.trust-line {
  max-width: 44rem;
  margin: 1.25rem 0 0;
  color: rgba(255, 253, 248, 0.62);
  font-family: var(--mono);
  font-size: 0.68rem;
  line-height: 1.55;
}

.trust-line strong {
  color: var(--paper-light);
}

.text-link,
.source-link {
  display: inline-block;
  min-height: 44px;
  padding-top: 0.55rem;
  border-bottom: 2px solid currentColor;
  font-weight: 800;
  text-decoration: none;
}

.text-link:hover,
.source-link:hover {
  color: var(--cobalt);
}

.hero .text-link:hover {
  color: var(--yellow);
}

.hero-link {
  margin-top: 1.8rem;
  color: var(--paper-light);
}

.hero-mark {
  position: relative;
  min-height: 22rem;
  padding: 1.35rem;
  border: 1px solid rgba(246, 241, 232, 0.34);
  background: linear-gradient(145deg, rgba(33, 97, 245, 0.25), rgba(9, 26, 40, 0.2));
}

.hero-mark::before,
.hero-mark::after {
  position: absolute;
  top: 1.05rem;
  bottom: 1.05rem;
  width: 0.4rem;
  border-top: 1px solid rgba(243, 201, 105, 0.6);
  border-bottom: 1px solid rgba(243, 201, 105, 0.6);
  content: "";
}

.hero-mark::before {
  left: 0.55rem;
}

.hero-mark::after {
  right: 0.55rem;
}

.hero-mark-head {
  display: flex;
  justify-content: space-between;
  color: var(--yellow);
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 800;
  letter-spacing: 0.16em;
}

.mark-rail {
  position: relative;
  height: 5rem;
  margin: 3.5rem 1.5rem 0;
}

.mark-rail--bottom {
  margin-top: 0.5rem;
}

.rail-line {
  position: absolute;
  top: 1.05rem;
  right: 1rem;
  left: 1rem;
  height: 0.25rem;
  background: var(--paper-light);
}

.rail-line::after {
  position: absolute;
  top: -0.4rem;
  right: 50%;
  width: 1px;
  height: 1.05rem;
  background: var(--yellow);
  content: "";
}

.rail-line--short {
  right: 3.1rem;
  left: 1rem;
  background: var(--cobalt);
}

.rail-dot {
  position: absolute;
  z-index: 1;
  top: 0.45rem;
  width: 1.45rem;
  height: 1.45rem;
  border: 0.28rem solid var(--ink);
  border-radius: 50%;
  background: var(--paper-light);
  box-shadow: 0 0 0 1px var(--paper-light);
}

.rail-dot--muted {
  left: 0;
  background: var(--slate);
}

.rail-dot--bright {
  right: 0;
  background: var(--yellow);
}

.rail-dot--warm {
  right: 0;
  background: var(--red);
}

.rail-caption {
  position: absolute;
  top: 2.25rem;
  color: rgba(255, 253, 248, 0.7);
  font-family: var(--mono);
  font-size: 0.66rem;
  text-transform: uppercase;
}

.rail-caption--left {
  left: -0.2rem;
}

.rail-caption--right {
  right: -0.3rem;
  color: var(--yellow);
}

.mark-arrow {
  margin-left: 46%;
  color: var(--yellow);
  font-size: 2rem;
  line-height: 1;
  transform: rotate(22deg);
}

.hero-mark-note {
  margin: 1.5rem 0 0;
  padding-top: 0.9rem;
  border-top: 1px solid rgba(246, 241, 232, 0.26);
  color: rgba(255, 253, 248, 0.74);
  font-size: 0.85rem;
  line-height: 1.35;
}

.hero-mark-note strong {
  color: var(--paper-light);
}

main {
  background: var(--paper);
}

.section {
  padding-top: clamp(4.5rem, 8vw, 8rem);
  padding-bottom: clamp(4.5rem, 8vw, 8rem);
}

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

.section-kicker {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 2.4rem;
  color: var(--cobalt-deep);
}

.section-kicker::after {
  width: 4rem;
  height: 0.3rem;
  background: var(--yellow);
  content: "";
}

.section-kicker > span:first-child {
  color: var(--red);
}

.section-kicker--inside {
  margin-bottom: 1rem;
  color: var(--yellow);
}

.section-kicker--inside::after {
  background: var(--red);
}

.section-grid {
  display: grid;
  gap: clamp(2.5rem, 7vw, 8rem);
}

.section-grid--answer {
  grid-template-columns: minmax(0, 0.92fr) minmax(19rem, 0.78fr);
  align-items: start;
}

.section-grid--wide {
  grid-template-columns: minmax(0, 0.77fr) minmax(0, 1.23fr);
  align-items: start;
}

.section-grid--ledger {
  grid-template-columns: minmax(0, 0.63fr) minmax(0, 1.37fr);
  align-items: start;
}

h2 {
  max-width: 14ch;
  margin-bottom: 1.35rem;
  font-size: clamp(2.55rem, 5vw, 5.3rem);
  line-height: 0.98;
}

h3 {
  margin-bottom: 0.55rem;
  font-size: clamp(1.45rem, 2.5vw, 2.25rem);
  line-height: 1.02;
}

p {
  margin-top: 0;
  margin-bottom: 1.2rem;
}

.lead {
  font-size: clamp(1.08rem, 1.45vw, 1.26rem);
  line-height: 1.55;
}

.section-intro > p:last-of-type,
.section--answer .section-grid > div > p:last-of-type {
  margin-bottom: 1.7rem;
}

.mechanism-list {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--ink);
}

.mechanism-list li {
  display: grid;
  grid-template-columns: 3.8rem 1fr;
  gap: 1rem;
  padding: 1.35rem 0;
  border-bottom: 1px solid var(--line);
}

.step-number {
  color: var(--red);
  font-family: var(--mono);
  font-size: 0.75rem;
  font-weight: 800;
}

.mechanism-list strong {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 1.1rem;
}

.mechanism-list p {
  margin: 0;
  color: var(--slate);
  font-size: 0.95rem;
  line-height: 1.45;
}

.section--threshold {
  background: #eee8de;
}

.threshold-figure {
  margin: 0;
  border: 1px solid var(--ink);
  background: var(--paper-light);
}

.threshold-figure svg {
  width: 100%;
  height: auto;
  padding: 1rem;
}

.threshold-figure figcaption {
  padding: 0.9rem 1.1rem 1.05rem;
  border-top: 1px solid var(--line);
  color: var(--slate);
  font-size: 0.78rem;
  line-height: 1.45;
}

.svg-axis {
  stroke: var(--ink);
  stroke-width: 3;
}

.svg-threshold {
  stroke: var(--red);
  stroke-dasharray: 5 8;
  stroke-width: 2;
}

.svg-branch {
  fill: none;
  stroke: var(--cobalt);
  stroke-width: 5;
}

.svg-node {
  stroke: var(--paper-light);
  stroke-width: 5;
}

.svg-node--muted {
  fill: var(--slate);
}

.svg-node--bright {
  fill: var(--yellow);
}

.svg-node--warm {
  fill: var(--red);
}

.svg-label {
  fill: var(--ink);
  font-family: var(--mono);
}

.svg-label--small {
  font-size: 14px;
  font-weight: 800;
  letter-spacing: 1px;
}

.svg-label--threshold,
.svg-label--number {
  fill: var(--red);
  font-size: 18px;
  font-weight: 800;
}

.svg-label--result {
  fill: var(--cobalt-deep);
  font-family: var(--display);
  font-size: 24px;
  font-weight: 700;
}

.interactive-card {
  margin-top: 3rem;
  padding: clamp(1.2rem, 3vw, 2.3rem);
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--paper-light);
}

.interactive-card--blue {
  background: var(--cobalt);
}

.interactive-heading {
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  align-items: end;
}

.interactive-heading h3 {
  max-width: 19ch;
  margin-bottom: 0;
}

.interaction-note {
  max-width: 22rem;
  margin: 0;
  color: rgba(255, 253, 248, 0.74);
  font-size: 0.78rem;
  line-height: 1.45;
}

.choice-fieldset {
  margin: 2rem 0 0;
  padding: 0;
  border: 0;
}

.choice-fieldset legend {
  margin-bottom: 0.7rem;
  color: rgba(255, 253, 248, 0.72);
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.choice-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.65rem;
}

.choice-fieldset--four .choice-row {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.choice-card {
  position: relative;
  display: block;
  min-width: 0;
  min-height: 4.1rem;
  border: 1px solid rgba(255, 253, 248, 0.48);
  cursor: pointer;
}

.choice-card:hover {
  border-color: var(--yellow);
}

.choice-card:has(input:checked) {
  border-color: var(--yellow);
  background: var(--yellow);
  color: var(--ink-deep);
}

.choice-card input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.choice-card-copy {
  display: flex;
  min-height: 4.1rem;
  flex-direction: column;
  justify-content: center;
  padding: 0.75rem 0.85rem;
}

.choice-card-copy strong {
  font-family: var(--display);
  font-size: 1.2rem;
  line-height: 1;
}

.choice-card-copy small {
  margin-top: 0.3rem;
  font-family: var(--mono);
  font-size: 0.64rem;
  line-height: 1.25;
  text-transform: uppercase;
}

.live-result {
  margin-top: 1.8rem;
  padding-top: 1.2rem;
  border-top: 1px solid rgba(255, 253, 248, 0.36);
}

.live-label {
  margin: 0 0 0.25rem;
  color: var(--yellow);
}

.live-number {
  margin: 0;
  color: var(--paper-light);
  font-family: var(--display);
  font-size: clamp(3.2rem, 8vw, 7.2rem);
  font-weight: 700;
  letter-spacing: -0.06em;
  line-height: 0.92;
}

.live-description {
  max-width: 38rem;
  margin: 0.75rem 0 0;
  color: rgba(255, 253, 248, 0.78);
  font-size: 1rem;
}

.next-question {
  max-width: 60rem;
  margin: 2.5rem 0 0 auto;
  padding-top: 1rem;
  border-top: 2px solid var(--red);
  font-size: 1.04rem;
  font-weight: 650;
}

.next-question span {
  display: block;
  margin-bottom: 0.35rem;
  color: var(--red);
}

.section--experiment {
  background: var(--paper-light);
}

.experiment-aside {
  display: flex;
  gap: 1.4rem;
  align-items: start;
}

.sample-stamp {
  flex: 0 0 9.5rem;
  min-height: 9.5rem;
  padding: 1rem;
  border: 1px solid var(--ink);
  background: var(--yellow);
  color: var(--ink-deep);
  transform: rotate(-2deg);
}

.stamp-number {
  display: block;
  font-family: var(--display);
  font-size: 3.25rem;
  font-weight: 700;
  letter-spacing: -0.08em;
  line-height: 0.9;
}

.stamp-label {
  display: block;
  margin-top: 1rem;
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 800;
  line-height: 1.35;
  text-transform: uppercase;
}

.small-note {
  max-width: 17rem;
  margin: 0.4rem 0 0;
  color: var(--slate);
  font-size: 0.78rem;
  line-height: 1.45;
}

.info-output {
  margin-top: 1.8rem;
  padding: 1.15rem;
  background: var(--paper-light);
  color: var(--ink);
}

.info-output-head {
  display: grid;
  grid-template-columns: minmax(10rem, 0.5fr) minmax(0, 1fr);
  gap: 1rem;
  align-items: start;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--line);
}

.info-output .live-label {
  color: var(--red);
}

.info-output-summary {
  margin: 0;
  font-weight: 750;
  line-height: 1.35;
}

.effect-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.effect-cell {
  min-width: 0;
  padding: 1.1rem 1rem 0.8rem 0;
  border-right: 1px solid var(--line);
}

.effect-cell + .effect-cell {
  padding-left: 1rem;
}

.effect-cell:last-child {
  border-right: 0;
}

.effect-cell span {
  display: block;
  min-height: 2.5rem;
  color: var(--slate);
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 800;
  line-height: 1.35;
  text-transform: uppercase;
}

.effect-cell strong {
  display: block;
  margin-top: 0.7rem;
  color: var(--cobalt-deep);
  font-family: var(--display);
  font-size: clamp(1.8rem, 4vw, 3.2rem);
  letter-spacing: -0.06em;
  line-height: 0.95;
}

.effect-cell--boundary strong {
  color: var(--red);
}

.info-output-note {
  margin: 0.95rem 0 0;
  padding-top: 0.9rem;
  border-top: 1px solid var(--line);
  color: var(--slate);
  font-size: 0.78rem;
  line-height: 1.45;
}

.section--boundary {
  background: var(--ink);
  color: var(--paper-light);
}

.section--boundary .section-kicker,
.section--boundary .next-question {
  color: var(--yellow);
}

.section--boundary .section-kicker::after {
  background: var(--red);
}

.boundary-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(20rem, 0.72fr);
  gap: clamp(2rem, 8vw, 9rem);
  align-items: start;
}

.section--boundary .lead {
  color: rgba(255, 253, 248, 0.9);
}

.section--boundary p:not(.section-kicker) {
  color: rgba(255, 253, 248, 0.74);
}

.section--boundary strong,
.boundary-card strong {
  color: var(--paper-light);
}

.boundary-card {
  padding: 1.3rem;
  border: 1px solid rgba(246, 241, 232, 0.44);
  background: rgba(33, 97, 245, 0.22);
}

.boundary-card-kicker {
  margin: 0 0 1.1rem;
  color: var(--yellow);
}

.boundary-line {
  display: grid;
  grid-template-columns: 2.2rem 1fr;
  gap: 0.65rem;
  align-items: start;
  padding: 1rem 0;
  border-top: 1px solid rgba(246, 241, 232, 0.25);
}

.boundary-line:first-of-type {
  border-top: 0;
}

.boundary-check,
.boundary-question {
  display: grid;
  width: 1.7rem;
  height: 1.7rem;
  place-items: center;
  border: 1px solid var(--yellow);
  color: var(--yellow);
  font-family: var(--mono);
  font-weight: 800;
}

.boundary-question {
  border-color: var(--red);
  color: var(--red);
}

.boundary-line strong {
  display: block;
  font-size: 1rem;
}

.boundary-line small {
  display: block;
  margin-top: 0.25rem;
  color: rgba(255, 253, 248, 0.65);
  font-size: 0.76rem;
  line-height: 1.35;
}

.section--ledger {
  background: var(--paper);
}

.ledger {
  border-top: 2px solid var(--ink);
}

.ledger-row {
  display: grid;
  grid-template-columns: minmax(6rem, 0.45fr) minmax(8rem, 0.7fr) minmax(0, 1.5fr);
  gap: 1rem;
  align-items: start;
  padding: 1.2rem 0;
  border-bottom: 1px solid var(--line);
}

.ledger-row--head {
  padding-top: 0.7rem;
  padding-bottom: 0.7rem;
  color: var(--slate);
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 800;
  letter-spacing: 0.1em;
}

.ledger-row strong {
  color: var(--cobalt-deep);
  font-family: var(--display);
  font-size: 1.65rem;
  letter-spacing: -0.05em;
  line-height: 0.98;
}

.ledger-row strong small {
  color: var(--red);
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.05em;
}

.ledger-row p {
  margin: 0;
  color: var(--slate);
  font-size: 0.9rem;
  line-height: 1.45;
}

.ledger-tag {
  color: var(--red);
}

.section--fences {
  background: #eee8de;
}

.section--fences > h2 {
  max-width: 12ch;
}

.fence-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 2.6rem;
}

.fence-card {
  min-height: 15rem;
  padding: 1.25rem;
  border: 1px solid var(--ink);
  background: var(--paper-light);
}

.fence-number {
  display: block;
  margin-bottom: 2.5rem;
  color: var(--red);
}

.fence-card h3 {
  margin-bottom: 0.55rem;
  font-size: 1.8rem;
}

.fence-card p {
  margin: 0;
  color: var(--slate);
  font-size: 0.9rem;
  line-height: 1.48;
}

.non-goal {
  max-width: 58rem;
  margin-top: 1rem;
  padding: 1.2rem 1.25rem;
  border-left: 0.5rem solid var(--cobalt);
  background: var(--yellow);
  color: var(--ink-deep);
  font-size: 1.02rem;
  line-height: 1.45;
}

.section--sources {
  background: var(--paper-light);
}

.source-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(18rem, 0.68fr);
  gap: clamp(2rem, 8vw, 8rem);
  align-items: start;
}

.source-link {
  color: var(--cobalt-deep);
}

.source-card {
  padding: 1.25rem;
  border: 1px solid var(--ink);
  background: var(--paper);
}

.source-card-kicker {
  margin-bottom: 1.15rem;
  color: var(--red);
}

.source-card dl {
  margin: 0;
}

.source-card dl > div {
  display: grid;
  grid-template-columns: 5.5rem 1fr;
  gap: 0.6rem;
  padding: 0.75rem 0;
  border-top: 1px solid var(--line);
}

.source-card dt {
  color: var(--slate);
  font-family: var(--mono);
  font-size: 0.65rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.source-card dd {
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.42;
}

.source-disclaimer {
  max-width: 56rem;
  margin: 3rem 0 0;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
  color: var(--slate);
  font-size: 0.8rem;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  padding-top: 2.5rem;
  padding-bottom: 3rem;
  background: var(--paper);
}

.site-footer .brand {
  display: inline-block;
  margin-bottom: 0.8rem;
}

.site-footer p {
  max-width: 26rem;
  margin: 0;
  color: var(--slate);
  font-size: 0.8rem;
  line-height: 1.45;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  align-content: start;
  justify-content: end;
  gap: 0.5rem 1.2rem;
  font-family: var(--mono);
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.footer-links a {
  min-height: 44px;
  padding: 0.7rem 0;
  text-decoration: none;
}

.footer-links a:hover {
  color: var(--cobalt-deep);
  text-decoration: underline;
  text-decoration-thickness: 2px;
}

@media (max-width: 960px) {
  .hero {
    grid-template-columns: minmax(0, 1fr);
    gap: 3rem;
  }

  .hero-mark {
    max-width: 42rem;
  }

  .section-grid--answer,
  .section-grid--wide,
  .section-grid--ledger,
  .boundary-grid,
  .source-grid {
    grid-template-columns: minmax(0, 1fr);
    gap: 2.7rem;
  }

  h2 {
    max-width: 16ch;
  }

  .choice-fieldset--four .choice-row {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .topbar,
  .hero,
  .section,
  .site-footer {
    width: min(100% - 2rem, 1240px);
  }

  .topbar {
    min-height: 4rem;
  }

  .brand {
    max-width: 15rem;
    font-size: 0.62rem;
    line-height: 1.35;
  }

  .hero {
    padding-top: 3.8rem;
    padding-bottom: 4.2rem;
  }

  h1 {
    max-width: 13ch;
    font-size: clamp(3rem, 14.2vw, 4.4rem);
  }

  .deck {
    font-size: 1rem;
  }

  .answer-strip {
    margin-top: 1.5rem;
    padding: 1rem 1rem 1.05rem;
  }

  .answer-strip p {
    font-size: 0.95rem;
  }

  .trust-line {
    font-size: 0.62rem;
  }

  .hero-mark {
    min-height: 18rem;
    padding: 1rem;
  }

  .mark-rail {
    margin-right: 0.8rem;
    margin-left: 0.8rem;
  }

  .section {
    padding-top: 4.2rem;
    padding-bottom: 4.2rem;
  }

  .section-kicker {
    margin-bottom: 1.7rem;
  }

  h2 {
    max-width: 14ch;
    font-size: clamp(2.7rem, 14vw, 4.2rem);
  }

  .lead {
    font-size: 1.08rem;
  }

  .interactive-heading,
  .experiment-aside,
  .site-footer {
    display: block;
  }

  .interaction-note {
    margin-top: 1rem;
  }

  .choice-row,
  .choice-fieldset--four .choice-row {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .choice-card-copy {
    padding-right: 0.6rem;
    padding-left: 0.6rem;
  }

  .choice-card-copy strong {
    font-size: 1.05rem;
  }

  .choice-card-copy small {
    font-size: 0.58rem;
  }

  .threshold-figure svg {
    min-width: 0;
    padding: 0.35rem;
  }

  .svg-label--small {
    font-size: 12px;
  }

  .svg-label--result {
    font-size: 20px;
  }

  .svg-label--number,
  .svg-label--threshold {
    font-size: 16px;
  }

  .effect-grid,
  .info-output-head {
    grid-template-columns: minmax(0, 1fr);
  }

  .effect-cell,
  .effect-cell + .effect-cell {
    padding: 0.9rem 0;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .effect-cell:last-child {
    border-bottom: 0;
  }

  .effect-cell span {
    min-height: 0;
  }

  .effect-cell strong {
    margin-top: 0.35rem;
  }

  .sample-stamp {
    width: 9rem;
    min-height: 9rem;
  }

  .ledger-row--head {
    display: none;
  }

  .ledger-row {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.5rem;
  }

  .ledger-row strong {
    font-size: 2rem;
  }

  .fence-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .fence-card {
    min-height: 0;
  }

  .fence-number {
    margin-bottom: 1.5rem;
  }

  .source-card dl > div {
    grid-template-columns: 4.5rem 1fr;
  }

  .footer-links {
    justify-content: start;
    margin-top: 1.5rem;
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}