.page-about {
  --about-gap: clamp(28px, 5vw, 64px);
  --about-line: rgba(11, 27, 43, 0.14);
  color: var(--ink);
}

.page-about .container {
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.page-about .crumbs {
  padding-block: 18px 6px;
  font-size: 13px;
  color: var(--mist);
}

.page-about .crumbs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .crumbs__item + .crumbs__item::before {
  content: "/";
  margin-right: 8px;
  color: var(--line-dark-strong);
}

.page-about .text-link {
  color: var(--ink);
  text-decoration-color: var(--cyan);
  text-underline-offset: 3px;
}

.page-about .text-link:hover {
  color: var(--cyan);
}

.page-about img {
  max-width: 100%;
  height: auto;
}

/* 首屏：左叙述，右竖排索引 */
.page-about .about-cover {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
  padding-block: clamp(26px, 5vw, 58px) clamp(34px, 6vw, 72px);
  position: relative;
}

.page-about .about-cover__text h1 {
  max-width: 18ch;
  margin: 12px 0 20px;
  font-family: var(--font-display);
  font-size: clamp(34px, 6vw, 58px);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-cover__text .lede {
  max-width: 60ch;
  margin: 0 0 18px;
  font-family: var(--font-serif);
  font-size: clamp(18px, 2.1vw, 22px);
  line-height: 1.75;
  color: var(--ink-soft);
}

.page-about .about-cover__text p {
  max-width: 62ch;
  margin: 0 0 14px;
  font-size: 16px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.page-about .about-cover__index {
  padding: 20px;
  background: var(--paper-2);
  border-top: 4px solid var(--cyan);
  border-radius: var(--radius-sm);
}

.page-about .about-index__label {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--mist);
}

.page-about .about-index__list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-index__item {
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink-soft);
}

.page-about .about-index__num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--cyan);
}

.page-about .about-index__sep {
  margin-inline: 5px;
  color: var(--line-dark-strong);
}

.page-about .about-index__name {
  font-weight: 600;
  color: var(--ink);
}

.page-about .about-index__hint {
  color: var(--mist);
  font-size: 12px;
}

/* 章节通用 */
.page-about .section {
  margin-block: clamp(44px, 8vw, 100px);
}

.page-about .section__head {
  max-width: 760px;
  margin-bottom: clamp(22px, 3.5vw, 36px);
}

.page-about .section__title {
  margin: 10px 0 12px;
  font-family: var(--font-display);
  font-size: clamp(26px, 4.2vw, 42px);
  font-weight: 700;
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .section__note {
  margin: 0;
  max-width: 60ch;
  font-family: var(--font-serif);
  font-size: 17px;
  line-height: 1.8;
  color: var(--ink-soft);
}

/* 时间轴画板 */
.page-about .about-timeline {
  padding: clamp(20px, 4vw, 38px);
  background: var(--paper-2);
  border: 1px solid var(--about-line);
  border-radius: var(--radius);
}

.page-about .about-timeline__media {
  margin: 0 0 clamp(24px, 4vw, 40px);
}

.page-about .about-timeline__media img {
  display: block;
  width: 100%;
  aspect-ratio: 2 / 1;
  object-fit: cover;
  border-radius: var(--radius-sm);
  filter: grayscale(0.35) saturate(0.85) contrast(1.05);
}

.page-about .media__caption {
  margin-top: 10px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--mist);
}

.page-about .timeline {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  top: 6px;
  bottom: 6px;
  left: 16px;
  width: 1px;
  background: var(--line-dark-strong);
}

.page-about .timeline__item {
  position: relative;
  padding-left: 42px;
  padding-block: 8px;
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: 10px;
  top: 32px;
  width: 13px;
  height: 13px;
  border: 2px solid var(--cyan);
  border-radius: 50%;
  background: var(--paper-2);
  z-index: 1;
}

.page-about .timeline__summary {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 16px 16px 15px;
  background: var(--card);
  border: 1px solid var(--about-line);
  border-radius: var(--radius-sm);
  cursor: pointer;
  list-style: none;
  transition: border-color 180ms var(--ease), background-color 180ms var(--ease);
}

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

.page-about .timeline__summary:hover {
  border-color: var(--cyan);
}

.page-about .timeline__summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.page-about .timeline__marker {
  flex: none;
}

.page-about .timeline__num {
  display: inline-block;
  padding: 4px 7px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--cyan);
  border: 1px solid var(--line-cyan);
  border-radius: 4px;
}

.page-about .timeline__title {
  display: block;
  font-family: var(--font-serif);
  font-size: clamp(18px, 2.5vw, 23px);
  font-weight: 600;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .timeline__meta {
  display: block;
  margin-top: 4px;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--mist);
}

.page-about .timeline__detail {
  padding: 14px 16px 8px 0;
}

.page-about .timeline__detail p {
  margin: 0;
  max-width: 66ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.page-about .timeline__item details[open] > .timeline__summary {
  border-color: var(--cyan);
  box-shadow: inset 3px 0 0 var(--cyan);
}

/* 运营分工 */
.page-about .about-ops__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
  align-items: start;
}

.page-about .duty-list {
  display: grid;
  gap: 10px;
}

.page-about .duty {
  padding: 14px 14px 14px 18px;
  border-left: 3px solid var(--about-line);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  transition: border-color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .duty:hover {
  border-left-color: var(--cyan);
  background: rgba(159, 227, 229, 0.16);
}

.page-about .duty__index {
  margin: 0 0 4px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  color: var(--mist);
}

.page-about .duty__title {
  margin: 0 0 6px;
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 600;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .duty__desc {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-soft);
}

.page-about .ops-figure {
  margin: 0;
}

.page-about .ops-figure img {
  display: block;
  width: 100%;
  aspect-ratio: 5 / 4;
  object-fit: cover;
  border-radius: var(--radius);
  filter: grayscale(0.4) saturate(0.8) contrast(1.05);
}

.page-about .ops-figure__caption {
  margin-top: 10px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--mist);
}

/* 四项检查 */
.page-about .about-checks__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
  align-items: start;
}

.page-about .check-list {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line-dark);
}

.page-about .check {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 14px;
  padding: 20px 0;
  border-bottom: 1px solid var(--line-dark);
}

.page-about .check__num {
  padding-top: 4px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

.page-about .check__title {
  margin: 0 0 5px;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .check__desc {
  margin: 0;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-soft);
}

.page-about .about-checks__note {
  padding: 24px;
  background: var(--paper-2);
  border: 1px solid var(--about-line);
  border-radius: var(--radius);
}

.page-about .about-checks__note-title {
  margin: 8px 0 10px;
  font-family: var(--font-serif);
  font-size: 22px;
  font-weight: 600;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .about-checks__note p {
  margin: 0 0 12px;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--ink-soft);
}

.page-about .about-checks__note .text-link {
  font-size: 14px;
  font-weight: 600;
}

/* 结尾深色面板 */
.page-about .about-close {
  position: relative;
  overflow: hidden;
  margin-block: clamp(46px, 8vw, 96px) 0;
  padding: clamp(28px, 5vw, 64px);
  background: var(--ink);
  color: var(--paper);
  border-radius: var(--radius);
  clip-path: polygon(0 1.8%, 100% 0, 100% 98.2%, 0 100%);
}

.page-about .about-close__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  max-width: none;
  object-fit: cover;
  opacity: 0.18;
  filter: grayscale(1) contrast(1.1);
}

.page-about .about-close__body {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 30px;
}

.page-about .about-close h2 {
  max-width: 18ch;
  margin: 10px 0 16px;
  font-family: var(--font-display);
  font-size: clamp(26px, 4vw, 40px);
  font-weight: 700;
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-close__text p {
  max-width: 56ch;
  margin: 0 0 12px;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(244, 239, 230, 0.84);
}

.page-about .about-close__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 20px;
}

.page-about .about-close .btn--ghost {
  border-color: var(--line-light);
  color: var(--paper);
}

.page-about .about-close .btn--ghost:hover {
  border-color: var(--cyan-soft);
  color: var(--cyan-soft);
}

.page-about .about-contact {
  padding-top: 18px;
  border-top: 1px solid var(--line-light);
}

.page-about .about-contact__list {
  display: grid;
  gap: 14px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-contact__list li {
  display: grid;
  gap: 3px;
}

.page-about .about-contact__label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  color: var(--cyan-soft);
}

.page-about .about-contact__value {
  font-size: 15px;
  line-height: 1.6;
  color: var(--paper);
  overflow-wrap: anywhere;
}

@media (min-width: 760px) {
  .page-about .about-ops__grid {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
  }

  .page-about .about-checks__grid {
    grid-template-columns: minmax(0, 1.2fr) minmax(250px, 0.8fr);
  }

  .page-about .about-close__body {
    grid-template-columns: minmax(0, 1.3fr) minmax(240px, 0.7fr);
    gap: 40px;
  }

  .page-about .about-contact {
    padding-top: 0;
    border-top: 0;
    padding-left: 24px;
    border-left: 1px solid var(--line-light);
  }
}

@media (min-width: 900px) {
  .page-about .about-cover {
    grid-template-columns: minmax(0, 1.55fr) minmax(240px, 0.65fr);
    align-items: end;
  }

  .page-about .about-cover__index {
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    min-height: 360px;
    padding: 24px 22px;
  }

  .page-about .about-index__list {
    flex-wrap: nowrap;
    gap: 16px;
    margin-top: 20px;
  }

  .page-about .about-index__item {
    writing-mode: vertical-rl;
    text-orientation: mixed;
    height: 258px;
    font-size: 15px;
    letter-spacing: 0.04em;
    line-height: 1.7;
  }

  .page-about .about-index__num,
  .page-about .about-index__name,
  .page-about .about-index__hint,
  .page-about .about-index__sep {
    display: inline;
  }

  .page-about .about-index__sep {
    margin-inline: 0 0;
  }

  .page-about .about-index__item + .about-index__item {
    padding-left: 14px;
    border-left: 1px solid var(--line-dark);
  }

  .page-about .timeline::before {
    left: 112px;
  }

  .page-about .timeline__item {
    padding-left: 148px;
  }

  .page-about .timeline__item::before {
    left: 106px;
    top: 34px;
  }

  .page-about .timeline__summary {
    padding: 18px 20px;
  }

  .page-about .timeline__detail {
    padding: 16px 20px 8px 0;
  }

  .page-about .about-timeline {
    padding: clamp(30px, 4vw, 48px);
  }
}

@media (min-width: 1120px) {
  .page-about .about-ops__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.92fr);
    gap: 56px;
  }

  .page-about .duty {
    padding-block: 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .timeline__summary,
  .page-about .duty {
    transition: none;
  }
}