:root {
  --u-green: #01BC77;
  --u-green-text: #008655;
  --u-ink: #1A1A1A;
  --u-white: #FFFFFF;
  --u-cream: #F0EBE0;
  --u-teal: #0D2D35;
  --u-line: #E8E8E8;
  --u-meta: #6B6B6B;
  --u-soft-green: #E6F7F0;
  --font-body: "Aeonik", "Inter", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --content: 72rem;
  color-scheme: light;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--u-white);
  color: var(--u-ink);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.55;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-underline-offset: .24em; }
a:hover { text-decoration-thickness: 2px; }
a:focus-visible, button:focus-visible, summary:focus-visible {
  outline: 3px solid #B86A00;
  outline-offset: 4px;
}
button { font: inherit; }
.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;
}
.skip-link {
  position: fixed;
  z-index: 100;
  top: 1rem;
  left: 1rem;
  transform: translateY(-200%);
  padding: .7rem 1rem;
  background: var(--u-white);
  border: 2px solid var(--u-ink);
}
.skip-link:focus { transform: none; }

.site-header {
  position: sticky;
  z-index: 20;
  top: 0;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 2rem;
  min-height: 68px;
  padding: 0 clamp(1.25rem, 4vw, 4rem);
  background: color-mix(in srgb, var(--u-white) 94%, transparent);
  border-bottom: 1px solid var(--u-line);
  backdrop-filter: blur(14px);
}
.wordmark { font-size: 1.45rem; font-weight: 750; text-decoration: none; letter-spacing: -.05em; }
.wordmark span { color: var(--u-green-text); }
.site-purpose { margin: 0; color: var(--u-meta); font-size: .75rem; letter-spacing: .1em; text-transform: uppercase; }
.site-header nav { display: flex; gap: 1.4rem; font-size: .85rem; }

.perspective { position: relative; background: var(--u-cream); }
.journey-thread {
  position: absolute;
  z-index: 5;
  top: 0;
  bottom: 0;
  left: max(1.25rem, calc((100% - var(--content)) / 2));
  width: 2px;
  background: color-mix(in srgb, var(--u-green) 24%, transparent);
}
.journey-thread span {
  position: sticky;
  top: 68px;
  display: block;
  width: 2px;
  height: min(58vh, 32rem);
  background: var(--u-green);
  animation: thread-arrival .9s ease-out both;
  transform-origin: top;
}
@keyframes thread-arrival { from { transform: scaleY(0); } to { transform: scaleY(1); } }

.chapter {
  position: relative;
  min-height: calc(100vh - 68px);
  display: grid;
  grid-template-columns: minmax(8rem, .35fr) minmax(0, 1fr);
  align-content: center;
  gap: clamp(2rem, 7vw, 8rem);
  max-width: var(--content);
  margin: 0 auto;
  padding: clamp(5rem, 11vh, 9rem) clamp(2.5rem, 6vw, 6rem);
  border-bottom: 1px solid color-mix(in srgb, var(--u-ink) 12%, transparent);
}
.chapter::before {
  content: "";
  position: absolute;
  z-index: 6;
  top: 50%;
  left: 0;
  width: 11px;
  height: 11px;
  border: 3px solid var(--u-cream);
  border-radius: 50%;
  background: var(--u-green);
  transform: translate(-4px, -50%);
}
.chapter-meta {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  color: var(--u-green-text);
  font-size: .72rem;
  font-weight: 750;
  letter-spacing: .12em;
  text-transform: uppercase;
}
.chapter-copy { max-width: 48rem; }
.eyebrow {
  margin: 0 0 1rem;
  color: var(--u-green-text);
  font-size: .72rem;
  font-weight: 750;
  letter-spacing: .14em;
  text-transform: uppercase;
}
h2 {
  max-width: 15ch;
  margin: 0 0 1.6rem;
  font-size: clamp(2.6rem, 6vw, 5.5rem);
  font-weight: 460;
  letter-spacing: -.055em;
  line-height: .98;
  text-wrap: balance;
}
.lead { max-width: 45rem; font-size: clamp(1.25rem, 2.2vw, 1.75rem); line-height: 1.35; }
.chapter-copy > p:not(.eyebrow, .lead, .boundary) { max-width: 42rem; color: #3E3E3E; }
.method-list, .trace-list { max-width: 46rem; margin: 2rem 0; padding: 0; list-style: none; counter-reset: method; }
.method-list li, .trace-list li {
  position: relative;
  padding: .8rem 0 .8rem 3.4rem;
  border-top: 1px solid color-mix(in srgb, var(--u-ink) 13%, transparent);
}
.method-list li { counter-increment: method; }
.method-list li::before {
  content: counter(method, decimal-leading-zero);
  position: absolute;
  left: 0;
  color: var(--u-green-text);
  font-size: .75rem;
  font-weight: 750;
  letter-spacing: .08em;
}
.trace-list li::before { content: ""; position: absolute; top: 1.4rem; left: .2rem; width: 1rem; height: 2px; background: var(--u-green); }
.boundary {
  max-width: 48rem;
  margin-top: 2rem;
  padding: 1rem 1.2rem;
  border-left: 3px solid var(--u-green);
  background: color-mix(in srgb, var(--u-white) 58%, transparent);
  color: #363636;
  font-size: .9rem;
}
.chapter-nav, .next-link {
  position: absolute;
  right: clamp(2.5rem, 6vw, 6rem);
  bottom: 2rem;
  display: flex;
  gap: 1.4rem;
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
}
.next-link { text-decoration: none; }
.primary-action {
  display: inline-flex;
  align-items: center;
  gap: 1rem;
  margin-top: 2rem;
  padding: .95rem 1.2rem;
  background: var(--u-green);
  color: var(--u-ink);
  font-weight: 750;
  text-decoration: none;
}

.chapter--bookend, .chapter--closing { max-width: none; background: var(--u-teal); color: var(--u-white); }
.chapter--bookend::before, .chapter--closing::before { left: max(1.25rem, calc((100% - var(--content)) / 2)); border-color: var(--u-teal); }
.chapter--bookend .chapter-meta, .chapter--closing .chapter-meta { margin-left: max(0rem, calc((100% - var(--content)) / 2)); color: #98E5C5; }
.chapter--bookend .chapter-copy, .chapter--closing .chapter-copy { max-width: 58rem; }
.chapter--bookend .chapter-copy > p:not(.eyebrow, .lead), .chapter--closing .chapter-copy > p:not(.eyebrow, .lead) { color: #D0DDDA; }
.chapter--bookend .eyebrow, .chapter--closing .eyebrow { color: #98E5C5; }
.chapter--bookend .next-link, .chapter--closing .chapter-nav { color: var(--u-white); }

.question-selector { padding: clamp(5rem, 10vw, 9rem) clamp(1.25rem, 5vw, 5rem); background: var(--u-white); }
.selector-intro, .question-list, .selector-footer { max-width: 62rem; margin: 0 auto; }
.selector-intro { margin-bottom: 4rem; }
.selector-intro h2 { max-width: 14ch; }
.question-list { border-top: 1px solid var(--u-line); }
.question { border-bottom: 1px solid var(--u-line); scroll-margin-top: 88px; }
.question summary {
  position: relative;
  display: grid;
  grid-template-columns: 3rem 1fr 2rem;
  gap: 1rem;
  align-items: center;
  min-height: 88px;
  padding: 1.2rem .3rem;
  cursor: pointer;
  font-size: clamp(1.15rem, 2.7vw, 1.7rem);
  font-weight: 570;
  line-height: 1.25;
  list-style: none;
}
.question summary::-webkit-details-marker { display: none; }
.question summary::after { content: "+"; font-size: 1.8rem; font-weight: 350; text-align: center; }
.question[open] summary::after { content: "−"; }
.question-number { color: var(--u-green-text); font-size: .73rem; font-weight: 800; letter-spacing: .1em; }
.question[data-selected="true"] { border-left: 4px solid var(--u-green); background: var(--u-soft-green); }
.question[data-selected="true"] summary { padding-left: 1rem; }
.selected-label { display: inline-block; margin: 0 0 1rem; color: #075E40; font-size: .72rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.question-body { padding: .25rem 3.3rem 2rem 4.3rem; max-width: 54rem; }
.question-body p { max-width: 48rem; }
.limitation { padding: 1rem 1.1rem; background: var(--u-white); border-left: 3px solid var(--u-ink); font-size: .92rem; }
.conditional-label { color: var(--u-green-text); font-size: .74rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.question button {
  min-height: 44px;
  padding: .65rem 1rem;
  border: 1px solid var(--u-ink);
  background: transparent;
  color: var(--u-ink);
  cursor: pointer;
  font-size: .85rem;
  font-weight: 700;
}
.selector-footer { margin-top: 4rem; padding-top: 2rem; border-top: 1px solid var(--u-line); }
.selector-footer > p:not(.boundary) { max-width: 48rem; }
footer { padding: 1.4rem clamp(1.25rem, 5vw, 5rem); background: var(--u-teal); color: #D0DDDA; font-size: .75rem; }
footer p { max-width: var(--content); margin: auto; }

@media (max-width: 700px) {
  body { font-size: 16px; }
  .site-header { grid-template-columns: auto 1fr; gap: 1rem; min-height: 60px; padding: 0 1rem; }
  .site-purpose { display: none; }
  .site-header nav { justify-self: end; gap: .8rem; font-size: .72rem; }
  .journey-thread { left: 1.25rem; }
  .journey-thread span { top: 60px; }
  .chapter, .chapter--bookend, .chapter--closing {
    min-height: auto;
    grid-template-columns: 1fr;
    gap: 1.7rem;
    padding: 5rem 1.35rem 5.5rem 3.1rem;
  }
  .chapter::before, .chapter--bookend::before, .chapter--closing::before { top: 5.35rem; left: 1.25rem; transform: translate(-4px, 0); }
  .chapter-meta, .chapter--bookend .chapter-meta, .chapter--closing .chapter-meta {
    margin: 0;
    flex-direction: row;
    justify-content: space-between;
  }
  h2 { font-size: clamp(2.35rem, 12vw, 4rem); }
  .lead { font-size: 1.2rem; }
  .chapter-nav, .next-link { right: 1.35rem; bottom: 1.5rem; }
  .method-list li, .trace-list li { padding-left: 2.7rem; }
  .question-selector { padding: 5rem 1.1rem; }
  .selector-intro { margin-bottom: 2.5rem; }
  .question summary { grid-template-columns: 2rem 1fr 1.6rem; gap: .6rem; min-height: 72px; font-size: 1.1rem; }
  .question-body { padding: .2rem .7rem 1.7rem 2.7rem; }
  .question[data-selected="true"] summary { padding-left: .7rem; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 0.001ms !important;
  }
}