.page-about {
  --about-rail: 168px;
  --about-gap: 32px;
  --about-line: #101215;
  background: var(--paper-0);
  color: var(--ink-900);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.85;
  padding: 26px 18px 88px;
  overflow-x: hidden;
}

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

.page-about a {
  color: inherit;
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: text-decoration-thickness var(--t-fast), color var(--t-fast);
}

.page-about a:hover {
  text-decoration-thickness: 2px;
  color: var(--accent-600);
}

.page-about .about-shell {
  max-width: var(--maxw);
  margin: 0 auto;
}

/* ---------- crumbs ---------- */
.page-about .crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-500);
  padding-bottom: 18px;
  border-bottom: 1px solid var(--paper-200);
}

.page-about .crumbs a {
  color: var(--ink-500);
  text-decoration: none;
}

.page-about .crumbs a:hover {
  color: var(--accent-600);
  text-decoration: underline;
}

.page-about .crumbs__sep {
  color: var(--paper-200);
}

/* ---------- hero ---------- */
.page-about .about-hero {
  display: grid;
  grid-template-columns: 1fr;
  gap: 26px;
  padding: 30px 0 34px;
  border-bottom: 1px solid var(--ink-900);
}

.page-about .about-hero__kicker {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--accent-600);
  margin: 0 0 14px;
}

.page-about .about-hero h1 {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(28px, 7vw, 42px);
  line-height: 1.28;
  margin: 0 0 18px;
  letter-spacing: -0.01em;
}

.page-about .about-hero__lede {
  font-size: 17px;
  line-height: 1.85;
  margin: 0 0 14px;
  max-width: 40em;
}

.page-about .about-hero__sub {
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-500);
  margin: 0;
  max-width: 40em;
  padding-left: 14px;
  border-left: 2px solid var(--accent-100);
}

.page-about .about-hero__media {
  position: relative;
  margin: 0;
  border: 1px solid var(--ink-900);
  padding: 10px;
  background: var(--paper-0);
}

.page-about .about-hero__corner {
  position: absolute;
  top: -1px;
  right: -1px;
  width: 26px;
  height: 26px;
  background: var(--accent-600);
  clip-path: polygon(100% 0, 0 0, 100% 100%);
}

.page-about .about-hero__media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
  border: 1px solid var(--paper-200);
}

.page-about .about-hero__caption {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--ink-500);
  line-height: 1.7;
  padding-top: 10px;
}

/* ---------- stats strip ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  border: 1px solid var(--ink-900);
  margin: 30px 0 0;
}

.page-about .about-stats__item {
  padding: 14px 14px 16px;
  border-bottom: 1px solid var(--paper-200);
  border-right: 1px solid var(--paper-200);
}

.page-about .about-stats__item:nth-child(2n) {
  border-right: 0;
}

.page-about .about-stats__item:nth-last-child(-n + 2) {
  border-bottom: 0;
}

.page-about .about-stats__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 24px;
  letter-spacing: 0.02em;
  color: var(--accent-600);
  line-height: 1.2;
}

.page-about .about-stats__label {
  display: block;
  font-size: 13px;
  color: var(--ink-500);
  margin-top: 6px;
  line-height: 1.6;
}

/* ---------- layout ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
  margin-top: 44px;
}

.page-about .about-index__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--ink-500);
  margin: 0 0 10px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--ink-900);
}

.page-about .about-index__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-index__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 7px 8px;
  font-size: 13.5px;
  line-height: 1.5;
  text-decoration: none;
  color: var(--ink-900);
  border-left: 2px solid transparent;
  transition: background var(--t-fast), border-color var(--t-fast), color var(--t-fast);
}

.page-about .about-index__num {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--ink-500);
  transition: color var(--t-fast);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  background: var(--accent-100);
  border-left-color: var(--accent-600);
  color: var(--accent-600);
}

.page-about .about-index__link:hover .about-index__num,
.page-about .about-index__link:focus-visible .about-index__num {
  color: var(--accent-600);
}

/* ---------- .page-about & chapters ---------- */
.page-about .about-body {
  min-width: 0;
  display: grid;
  gap: 0;
}

.page-about .about-chapter {
  scroll-margin-top: 24px;
  padding-top: 34px;
}

.page-about .about-chapter:first-child {
  padding-top: 0;
}

.page-about .about-chapter + .about-chapter {
  margin-top: 44px;
  border-top: 1px solid var(--paper-200);
}

.page-about .about-chapter__head {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex-wrap: wrap;
  padding-top: 10px;
  border-top: 1px solid var(--ink-900);
  margin-bottom: 22px;
}

.page-about .about-chapter__num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--accent-600);
  flex: 0 0 auto;
}

.page-about .about-chapter__title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(21px, 5vw, 29px);
  line-height: 1.36;
  margin: 0;
  flex: 1 1 auto;
  min-width: 0;
}

.page-about .about-chapter__rule {
  flex: 0 0 auto;
  width: 42px;
  height: 5px;
  background-image: repeating-linear-gradient(
    to right,
    var(--index-400) 0 1px,
    transparent 1px 6px
  );
  align-self: center;
}

.page-about .about-chapter__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 20px;
}

.page-about .about-chapter__main {
  min-width: 0;
}

.page-about .about-chapter__aside {
  min-width: 0;
  border-top: 1px solid var(--paper-200);
  padding-top: 14px;
}

.page-about .prose p {
  margin: 0 0 16px;
}

.page-about .prose p:last-child {
  margin-bottom: 0;
}

/* ---------- notes / details ---------- */
.page-about .about-note {
  border-left: 2px solid var(--accent-600);
  padding: 2px 0 2px 12px;
  margin-bottom: 14px;
}

.page-about .about-note__summary {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--ink-900);
  cursor: pointer;
  list-style: none;
  line-height: 1.6;
}

.page-about .about-note__summary::-webkit-details-marker {
  display: none;
}

.page-about .about-note__summary::before {
  content: "＋ ";
  color: var(--accent-600);
  font-family: var(--font-mono);
}

.page-about .about-note[open] .about-note__summary::before {
  content: "－ ";
}

.page-about .about-note__summary:hover {
  color: var(--accent-600);
}

.page-about .about-note__body {
  font-size: 14px;
  line-height: 1.78;
  color: var(--ink-500);
  margin: 10px 0 0;
}

.page-about .about-aside-meta {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  line-height: 1.7;
  color: var(--ink-500);
  margin: 0;
  padding-left: 12px;
  border-left: 2px solid var(--paper-200);
}

/* ---------- scenes ---------- */
.page-about .about-scenes {
  display: grid;
  gap: 0;
  margin: 6px 0 20px;
  border-top: 1px solid var(--paper-200);
}

.page-about .about-scene {
  padding: 14px 0 16px;
  border-bottom: 1px solid var(--paper-200);
}

.page-about .about-scene__tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--ink-900);
  background: var(--paper-200);
  padding: 2px 7px;
  margin-bottom: 8px;
}

.page-about .about-scene__title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 17px;
  line-height: 1.5;
  margin: 0 0 6px;
}

.page-about .about-scene__text {
  font-size: 15px;
  line-height: 1.78;
  color: var(--ink-500);
  margin: 0;
}

/* ---------- roles ---------- */
.page-about .about-roles {
  list-style: none;
  margin: 6px 0 20px;
  padding: 0;
  border-top: 1px solid var(--ink-900);
}

.page-about .about-roles__item {
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr);
  gap: 14px;
  padding: 14px 0;
  border-bottom: 1px solid var(--paper-200);
  transition: background var(--t-fast);
}

.page-about .about-roles__item:hover {
  background: var(--accent-100);
}

.page-about .about-roles__num {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--accent-600);
  padding-top: 2px;
}

.page-about .about-roles__title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 17px;
  line-height: 1.5;
  margin: 0 0 5px;
}

.page-about .about-roles__text {
  font-size: 15px;
  line-height: 1.78;
  color: var(--ink-500);
  margin: 0;
}

/* ---------- figures ---------- */
.page-about .about-figure {
  margin: 22px 0;
  border: 1px solid var(--ink-900);
  padding: 10px;
  background: var(--paper-0);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--paper-200);
}

.page-about .about-figure--flow img {
  aspect-ratio: 9 / 7;
  object-fit: cover;
}

.page-about .about-figure--timeline img {
  aspect-ratio: 2 / 1;
  object-fit: cover;
}

.page-about .about-figure__caption {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  line-height: 1.7;
  color: var(--ink-500);
  padding-top: 10px;
}

/* ---------- flow steps ---------- */
.page-about .about-flow {
  list-style: none;
  margin: 0 0 22px;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .about-flow__step {
  border: 1px solid var(--paper-200);
  padding: 14px 16px;
  transition: border-color var(--t-fast), background var(--t-fast);
}

.page-about .about-flow__step:hover {
  border-color: var(--ink-900);
  background: var(--accent-100);
}

.page-about .about-flow__idx {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--accent-600);
  padding-bottom: 8px;
  margin-bottom: 10px;
  border-bottom: 1px solid var(--paper-200);
}

.page-about .about-flow__text {
  font-size: 15px;
  line-height: 1.78;
  margin: 0;
}

/* ---------- timeline ---------- */
.page-about .about-timeline {
  list-style: none;
  margin: 26px 0 24px;
  padding: 0 0 0 24px;
  border-left: 1px solid var(--paper-200);
}

.page-about .about-timeline__item {
  position: relative;
  padding: 0 0 28px;
}

.page-about .about-timeline__item:last-child {
  padding-bottom: 0;
}

.page-about .about-timeline__dot {
  position: absolute;
  left: -28px;
  top: 8px;
  width: 8px;
  height: 8px;
  background: var(--ink-900);
  transition: background var(--t-fast), transform var(--t-fast);
}

.page-about .about-timeline__item:hover .about-timeline__dot {
  background: var(--accent-600);
  transform: scale(1.25);
}

.page-about .about-timeline__year {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--ink-900);
  padding: 1px 7px;
  border: 1px solid var(--ink-900);
  margin-bottom: 8px;
  transition: background var(--t-fast), color var(--t-fast);
}

.page-about .about-timeline__item:hover .about-timeline__year {
  background: var(--accent-600);
  color: var(--paper-0);
  border-color: var(--accent-600);
}

.page-about .about-timeline__title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 18px;
  line-height: 1.5;
  margin: 0 0 6px;
}

.page-about .about-timeline__desc {
  font-size: 15px;
  line-height: 1.78;
  color: var(--ink-500);
  margin: 0;
}

.page-about .about-timeline__hint {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.04em;
  line-height: 1.7;
  color: var(--ink-500);
  opacity: 0.5;
  margin: 8px 0 0;
  padding-left: 10px;
  border-left: 2px solid var(--paper-200);
  transition: opacity var(--t-mid), color var(--t-mid), border-color var(--t-mid);
}

.page-about .about-timeline__item:hover .about-timeline__hint {
  opacity: 1;
  color: var(--teal-700);
  border-left-color: var(--teal-700);
}

/* ---------- correction list ---------- */
.page-about .about-correct {
  list-style: none;
  margin: 4px 0 18px;
  padding: 0;
  border-top: 1px solid var(--paper-200);
}

.page-about .about-correct__item {
  font-size: 15px;
  line-height: 1.78;
  color: var(--ink-500);
  padding: 10px 0;
  border-bottom: 1px solid var(--paper-200);
}

.page-about .about-correct__k {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--ink-900);
  margin-right: 8px;
  padding: 1px 6px;
  border: 1px solid var(--ink-900);
}

.page-about .about-end {
  padding-top: 14px;
  border-top: 1px solid var(--ink-900);
  font-size: 15px;
  line-height: 1.85;
}

/* ---------- chapter transition index line ---------- */
.page-about .index-line {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 34px 0 0;
  padding: 8px 0;
  border-top: 1px solid var(--paper-200);
  border-bottom: 1px solid var(--paper-200);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--ink-500);
}

.page-about .index-line__num {
  color: var(--accent-600);
}

.page-about .index-line__text {
  flex: 0 1 auto;
}

.page-about .index-line__ticks {
  flex: 1 1 auto;
  height: 5px;
  min-width: 30px;
  background-image: repeating-linear-gradient(
    to right,
    var(--ink-500) 0 1px,
    transparent 1px 7px
  );
  opacity: 0.45;
}

/* ---------- responsive ---------- */
@media (min-width: 640px) {
  .page-about {
    padding: 34px 28px 96px;
    --about-gap: 38px;
  }

  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-stats__item {
    border-right: 1px solid var(--paper-200);
    border-bottom: 0;
  }

  .page-about .about-stats__item:last-child {
    border-right: 0;
  }

  .page-about .about-stats__item:nth-child(2n) {
    border-right: 1px solid var(--paper-200);
  }

  .page-about .about-stats__num {
    font-size: 27px;
  }

  .page-about .about-scenes {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    border-bottom: 1px solid var(--paper-200);
  }

  .page-about .about-scene {
    padding: 16px 16px 18px;
    border-bottom: 0;
    border-right: 1px solid var(--paper-200);
  }

  .page-about .about-scene:first-child {
    padding-left: 0;
  }

  .page-about .about-scene:last-child {
    border-right: 0;
    padding-right: 0;
  }

  .page-about .about-flow {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0;
  }

  .page-about .about-flow__step {
    border-right: 0;
    padding: 16px 14px 18px;
  }

  .page-about .about-flow__step:last-child {
    border-right: 1px solid var(--paper-200);
  }

  .page-about .about-flow__step:hover {
    border-right: 1px solid var(--ink-900);
  }
}

@media (min-width: 900px) {
  .page-about {
    font-size: 17.5px;
  }

  .page-about .about-chapter__grid {
    grid-template-columns: minmax(0, var(--col-main)) minmax(0, var(--col-note));
    gap: 34px;
  }

  .page-about .about-chapter__main {
    max-width: var(--col-main);
  }

  .page-about .about-chapter__aside {
    border-top: 0;
    padding-top: 3px;
  }
}

@media (min-width: 1060px) {
  .page-about {
    --about-gap: 52px;
  }

  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: var(--about-gap);
    margin-top: 56px;
  }

  .page-about .about-index {
    position: sticky;
    top: 32px;
    align-self: start;
  }

  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.12fr) minmax(0, 0.88fr);
    gap: 38px;
    align-items: start;
    padding: 40px 0 44px;
  }

  .page-about .about-chapter + .about-chapter {
    margin-top: 68px;
    padding-top: 44px;
  }

  .page-about .about-timeline {
    padding-left: 32px;
    margin-left: 6px;
  }

  .page-about .about-timeline__dot {
    left: -36px;
  }

  .page-about .about-timeline__item {
    display: grid;
    grid-template-columns: 76px minmax(0, 1fr);
    column-gap: 18px;
    align-items: start;
  }

  .page-about .about-timeline__year {
    grid-column: 1;
    justify-self: start;
    margin-bottom: 0;
  }

  .page-about .about-timeline__title,
  .page-about .about-timeline__desc,
  .page-about .about-timeline__hint {
    grid-column: 2;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about a,
  .page-about .about-index__link,
  .page-about .about-note__summary,
  .page-about .about-flow__step,
  .page-about .about-roles__item,
  .page-about .about-timeline__dot,
  .page-about .about-timeline__year,
  .page-about .about-timeline__hint {
    transition: color var(--t-fast), background-color var(--t-fast), border-color var(--t-fast);
  }

  .page-about .about-timeline__item:hover .about-timeline__dot {
    transform: none;
  }
}