.page-about {
  --ab-gap: clamp(20px, 3.4vw, 48px);
  --ab-pad: clamp(18px, 2.6vw, 30px);
}

/* 面包屑 */
.page-about .ab-crumbs {
  padding-top: 16px;
}
.page-about .ab-crumbs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.07em;
  color: var(--ink-soft);
}
.page-about .ab-crumbs__item {
  display: flex;
  align-items: center;
  gap: 8px;
}
.page-about .ab-crumbs__item + .ab-crumbs__item::before {
  content: "/";
  color: var(--line);
}
.page-about .ab-crumbs .breadcrumbs__link {
  color: var(--ink-soft);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .ab-crumbs a.breadcrumbs__link:hover,
.page-about .ab-crumbs a.breadcrumbs__link:focus-visible {
  color: var(--ink);
  border-bottom-color: var(--cyan);
}
.page-about .ab-crumbs [aria-current="page"] {
  color: var(--cyan);
}

/* 首屏 */
.page-about .ab-hero {
  position: relative;
  padding-top: clamp(22px, 4vw, 48px);
  padding-bottom: clamp(24px, 4vw, 52px);
}
.page-about .ab-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(59, 68, 74, 0.28) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(59, 68, 74, 0.16) 1px, transparent 1px);
  background-size: 88px 88px;
  mask-image: radial-gradient(120% 90% at 20% 0%, #000 0%, transparent 78%);
  -webkit-mask-image: radial-gradient(120% 90% at 20% 0%, #000 0%, transparent 78%);
}
.page-about .ab-hero__grid {
  position: relative;
  display: grid;
  gap: var(--ab-gap);
}
.page-about .ab-hero__title {
  margin: 14px 0 0;
  max-width: 15ch;
  font-size: clamp(38px, 7.2vw, 84px);
  line-height: 0.98;
  letter-spacing: -0.01em;
}
.page-about .ab-hero__lede {
  margin: 22px 0 0;
  max-width: 56ch;
  color: var(--ink-soft);
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.8;
}

.page-about .ab-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .ab-stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
  background: var(--panel);
}
.page-about .ab-stat__num {
  font-family: var(--font-display);
  font-size: clamp(28px, 4.6vw, 42px);
  font-weight: 600;
  line-height: 1;
  color: var(--cyan);
}
.page-about .ab-stat:nth-child(2) .ab-stat__num {
  color: var(--orange);
}
.page-about .ab-stat__label {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.07em;
  color: var(--ink-soft);
  line-height: 1.5;
}

.page-about .ab-hero__side {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 16px;
  align-items: start;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}
.page-about .ab-hero__rail {
  display: none;
  margin: 0;
  writing-mode: vertical-rl;
  font-size: 10.5px;
  letter-spacing: 0.24em;
  color: var(--ink-soft);
}
.page-about .ab-jump__title {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--cyan);
}
.page-about .ab-jump__list {
  display: grid;
  gap: 2px;
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
}
.page-about .ab-jump__link {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 9px 10px;
  min-height: 44px;
  box-sizing: border-box;
  color: var(--ink);
  font-size: 14px;
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .ab-jump__link .mono {
  color: var(--ink-soft);
  font-size: 11px;
  letter-spacing: 0.1em;
}
.page-about .ab-jump__link:hover,
.page-about .ab-jump__link:focus-visible {
  background: var(--panel-2);
  border-left-color: var(--cyan);
}
.page-about .ab-jump__link:hover .mono,
.page-about .ab-jump__link:focus-visible .mono {
  color: var(--cyan);
}

/* 章节头 */
.page-about .ab-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  margin-bottom: clamp(20px, 3vw, 34px);
  padding-top: 18px;
  border-top: 1px solid var(--line);
}
.page-about .ab-head__no {
  margin: 0;
  padding-top: 8px;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--cyan);
}
.page-about .ab-head h2 {
  margin: 0;
}
.page-about .ab-head__sub {
  margin: 12px 0 0;
  max-width: 64ch;
  color: var(--ink-soft);
  font-size: 15px;
  line-height: 1.8;
}

/* 主张三块 */
.page-about .ab-claim {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .ab-claim__item {
  position: relative;
  padding: var(--ab-pad);
  background: var(--panel);
  transition: background var(--dur) var(--ease);
}
.page-about .ab-claim__item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--line);
}
.page-about .ab-claim__item:nth-child(1)::before {
  background: var(--cyan);
}
.page-about .ab-claim__item:nth-child(2)::before {
  background: var(--orange);
}
.page-about .ab-claim__item:nth-child(3)::before {
  background: var(--yellow);
}
.page-about .ab-claim__item:hover,
.page-about .ab-claim__item:focus-within {
  background: var(--panel-2);
}
.page-about .ab-claim__no {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--ink-soft);
}
.page-about .ab-claim__item h3 {
  margin: 12px 0 0;
}
.page-about .ab-claim__item > p {
  margin: 12px 0 0;
  color: var(--ink-soft);
  font-size: 14.5px;
  line-height: 1.8;
}
.page-about .ab-claim__list {
  display: grid;
  gap: 8px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  font-size: 13.5px;
  color: var(--ink);
}
.page-about .ab-claim__list li {
  position: relative;
  padding-left: 18px;
}
.page-about .ab-claim__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.68em;
  width: 8px;
  height: 1px;
  background: var(--cyan);
}

/* 团队分工 */
.page-about .ab-crew {
  display: grid;
  gap: var(--ab-gap);
}
.page-about .ab-group {
  position: relative;
  padding: 2px 0 20px 18px;
  border-left: 1px solid var(--line);
}
.page-about .ab-group:last-of-type {
  padding-bottom: 6px;
}
.page-about .ab-group::before {
  content: "";
  position: absolute;
  left: -4px;
  top: 7px;
  width: 7px;
  height: 7px;
  background: var(--cyan);
}
.page-about .ab-group:nth-child(2)::before {
  background: var(--orange);
}
.page-about .ab-group:nth-child(3)::before {
  background: var(--yellow);
}
.page-about .ab-group__head {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 14px;
  align-items: baseline;
}
.page-about .ab-group__name {
  margin: 0;
  font-size: 17px;
  letter-spacing: 0.01em;
}
.page-about .ab-group__size {
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--cyan);
}
.page-about .ab-group p {
  margin: 8px 0 0;
  color: var(--ink-soft);
  font-size: 14.5px;
  line-height: 1.8;
}
.page-about .ab-crew__note {
  margin: 22px 0 0;
  padding: 14px 16px;
  background: var(--panel);
  border-left: 2px solid var(--orange);
  color: var(--ink);
  font-size: 14px;
  line-height: 1.75;
}
.page-about .ab-crew__fig,
.page-about .ab-books__fig,
.page-about .ab-tl__fig {
  margin: 0;
}
.page-about .ab-crew__fig .media-frame,
.page-about .ab-books__fig .media-frame,
.page-about .ab-tl__fig .media-frame {
  border: 1px solid var(--line);
  background: var(--panel);
}
.page-about .ab-crew__fig img,
.page-about .ab-books__fig img,
.page-about .ab-tl__fig img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}
.page-about .ab-figcap {
  margin: 10px 0 0;
  font-size: 11.5px;
  line-height: 1.7;
  letter-spacing: 0.04em;
  color: var(--ink-soft);
}

/* 手册封面 */
.page-about .ab-covers {
  display: grid;
  gap: 12px;
  margin-bottom: 16px;
}
.page-about .ab-cover {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 22px;
  min-height: 168px;
  padding: 20px;
  overflow: hidden;
  border: 1px solid var(--line);
  background: linear-gradient(163deg, #1A2024 0%, #101416 72%);
}
.page-about .ab-cover::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 3px;
  background: var(--cyan);
}
.page-about .ab-cover--orange::after {
  background: var(--orange);
}
.page-about .ab-cover--yellow::after {
  background: var(--yellow);
}
.page-about .ab-cover__no {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--ink-soft);
}
.page-about .ab-cover__name {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(22px, 2.6vw, 30px);
  line-height: 1.1;
  color: var(--ink);
}
.page-about .ab-cover__meta {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
}

/* 手册条目 */
.page-about .ab-books__body {
  display: grid;
  gap: var(--ab-gap);
}
.page-about .ab-sheets {
  display: grid;
  gap: 10px;
  align-content: start;
}
.page-about .ab-sheet {
  background: var(--panel);
  border: 1px solid var(--line);
}
.page-about .ab-sheet summary {
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 48px;
  padding: 14px 16px;
  box-sizing: border-box;
  list-style: none;
  cursor: pointer;
  color: var(--ink);
  font-size: 15.5px;
  transition: background var(--dur) var(--ease);
}
.page-about .ab-sheet summary::-webkit-details-marker {
  display: none;
}
.page-about .ab-sheet summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--cyan);
  transition: transform var(--dur) var(--ease);
}
.page-about .ab-sheet[open] summary::after {
  transform: rotate(45deg);
}
.page-about .ab-sheet summary:hover {
  background: var(--panel-2);
}
.page-about .ab-sheet summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: -2px;
}
.page-about .ab-sheet__key {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--cyan);
}
.page-about .ab-sheet__body {
  padding: 4px 16px 16px;
  border-top: 1px solid var(--line);
}
.page-about .ab-sheet__body ul {
  display: grid;
  gap: 9px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-soft);
}
.page-about .ab-sheet__body li {
  position: relative;
  padding-left: 18px;
}
.page-about .ab-sheet__body li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 8px;
  height: 1px;
  background: var(--teal);
}

/* 时间线 */
.page-about .ab-tl {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .ab-tl::before {
  content: "";
  position: absolute;
  top: 8px;
  bottom: 8px;
  left: 6px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan) 0%, var(--teal) 55%, var(--line) 100%);
}
.page-about .ab-tl__item {
  position: relative;
  padding: 0 0 30px 34px;
}
.page-about .ab-tl__item:last-child {
  padding-bottom: 0;
}
.page-about .ab-tl__dot {
  position: absolute;
  top: 5px;
  left: 0;
  width: 13px;
  height: 13px;
  background: var(--bg);
  border: 1px solid var(--cyan);
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .ab-tl__item:hover .ab-tl__dot,
.page-about .ab-tl__item:focus-within .ab-tl__dot {
  background: var(--orange);
  border-color: var(--orange);
}
.page-about .ab-tl__tag {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--ink-soft);
}
.page-about .ab-tl__title {
  margin: 7px 0 0;
  font-family: var(--font-display);
  font-size: clamp(19px, 2.4vw, 25px);
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--ink);
}
.page-about .ab-tl__text {
  margin: 8px 0 0;
  max-width: 62ch;
  color: var(--ink-soft);
  font-size: 15px;
  line-height: 1.8;
}
.page-about .ab-tl__more {
  margin-top: 10px;
}
.page-about .ab-tl__more ul {
  display: grid;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.7;
  color: var(--ink-soft);
}
.page-about .ab-tl__fig {
  margin-top: clamp(24px, 4vw, 40px);
}

/* 协作 */
.page-about .ab-coop-sec {
  padding-bottom: clamp(32px, 5vw, 64px);
}
.page-about .ab-coop {
  display: grid;
  gap: var(--ab-gap);
}
.page-about .ab-coop__lead h2 {
  margin: 0;
  max-width: 18ch;
}
.page-about .ab-coop__lead p {
  margin: 16px 0 0;
  max-width: 52ch;
  color: var(--ink-soft);
  font-size: 15px;
  line-height: 1.85;
}
.page-about .ab-coop__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 24px;
}
.page-about .ab-coop__list {
  display: grid;
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .ab-coop__list li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  padding: 18px;
  background: var(--panel);
  transition: background var(--dur) var(--ease);
}
.page-about .ab-coop__list li:hover {
  background: var(--panel-2);
}
.page-about .ab-coop__idx {
  padding-top: 3px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--orange);
}
.page-about .ab-coop__list h3 {
  margin: 0;
  font-size: 15.5px;
  font-weight: 600;
  letter-spacing: 0.01em;
}
.page-about .ab-coop__list p {
  margin: 7px 0 0;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.75;
}

/* 断点 */
@media (min-width: 720px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .ab-covers {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .ab-claim__item > p {
    max-width: 44ch;
  }
}

@media (min-width: 900px) {
  .page-about .ab-crew {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: start;
  }
  .page-about .ab-books__body {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 0.75fr);
    align-items: start;
  }
  .page-about .ab-coop {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
    align-items: start;
  }
}

@media (min-width: 860px) {
  .page-about .ab-claim {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.85fr) minmax(0, 1.35fr);
  }
}

@media (min-width: 960px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1fr) 252px;
    gap: clamp(24px, 4vw, 56px);
    align-items: start;
  }
  .page-about .ab-hero__side {
    padding: 0 0 0 20px;
    border-top: 0;
    border-left: 1px solid var(--line);
  }
  .page-about .ab-hero__rail {
    display: block;
  }
  .page-about .ab-head {
    grid-template-columns: 56px minmax(0, 1fr);
    gap: 20px;
  }
}

@media (hover: hover) and (min-width: 900px) {
  .page-about .ab-tl__more {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 220ms var(--ease), opacity 180ms var(--ease);
  }
  .page-about .ab-tl__item:hover .ab-tl__more,
  .page-about .ab-tl__item:focus-within .ab-tl__more {
    max-height: 220px;
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-jump__link,
  .page-about .ab-claim__item,
  .page-about .ab-sheet summary,
  .page-about .ab-sheet summary::after,
  .page-about .ab-tl__dot,
  .page-about .ab-tl__more,
  .page-about .ab-coop__list li,
  .page-about .ab-crumbs .breadcrumbs__link {
    transition: none;
  }
  .page-about .ab-tl__more {
    max-height: none;
    opacity: 1;
    overflow: visible;
  }
}