.page-about {
  --ab-rail: 208px;
  --ab-line: rgba(58, 74, 112, .55);
  --ab-panel: rgba(22, 36, 79, .58);
  display: block;
  background: var(--yk-ink);
  color: var(--yk-mist);
  font-family: var(--yk-font-body);
  overflow-x: clip;
}

.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--yk-teal);
  outline-offset: 2px;
}

/* ---------- 页首 ---------- */

.page-about .ab-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: clamp(24px, 5vw, 56px) 0 clamp(34px, 6vw, 76px);
  border-bottom: 1px solid var(--ab-line);
}

.page-about .ab-hero__bg {
  position: absolute;
  inset: 0;
  z-index: -1;
}

.page-about .ab-hero__bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .3;
  filter: saturate(.75);
}

.page-about .ab-hero__bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(120% 90% at 10% 0%, rgba(55, 245, 193, .12), transparent 62%),
    linear-gradient(180deg, rgba(5, 10, 24, .58) 0%, rgba(5, 10, 24, .93) 62%, var(--yk-ink) 100%);
}

.page-about .ab-hero__inner {
  position: relative;
}

.page-about .yk-crumb a {
  color: var(--yk-haze);
  text-decoration: none;
}

.page-about .yk-crumb a:hover {
  color: var(--yk-teal);
}

.page-about .ab-hero__title {
  max-width: 22ch;
  margin: 14px 0 0;
  font-family: var(--yk-font-head);
  font-weight: 900;
  font-size: clamp(30px, 6.4vw, 62px);
  line-height: 1.06;
  letter-spacing: -.01em;
  color: var(--yk-mist);
}

.page-about .ab-hero__lede {
  max-width: 56ch;
  margin: 18px 0 0;
  font-size: clamp(15px, 1.5vw, 17px);
  line-height: 1.72;
  color: var(--yk-haze);
}

.page-about .ab-hero__facts {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .ab-fact {
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding: 9px 16px;
  border-radius: var(--yk-r4);
  background: rgba(11, 23, 51, .7);
  border: 1px solid var(--ab-line);
}

.page-about .ab-fact__k {
  font-family: var(--yk-font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--yk-haze);
}

.page-about .ab-fact__v {
  font-size: 15px;
  font-weight: 700;
  color: var(--yk-teal);
}

/* ---------- 主体骨架 ---------- */

.page-about .ab-body {
  padding: clamp(34px, 6vw, 68px) 0 clamp(48px, 8vw, 100px);
}

.page-about .ab-body__inner {
  display: grid;
  gap: 26px;
  align-items: start;
}

@media (min-width: 1000px) {
  .page-about .ab-body__inner {
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: clamp(32px, 5vw, 76px);
  }
}

/* ---------- 左侧展签栏 ---------- */

.page-about .ab-rail {
  border-bottom: 1px solid var(--ab-line);
  padding-bottom: 14px;
}

.page-about .ab-rail__title {
  margin: 0 0 10px;
  font-family: var(--yk-font-mono);
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--yk-haze);
  text-transform: uppercase;
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .ab-rail__link {
  display: block;
  padding: 8px 14px;
  border-radius: var(--yk-r4);
  border: 1px solid transparent;
  background: rgba(11, 23, 51, .6);
  color: var(--yk-haze);
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  transition: color .2s var(--yk-ease), background .2s var(--yk-ease), border-color .2s var(--yk-ease);
}

.page-about .ab-rail__link:hover,
.page-about .ab-rail__link:focus-visible {
  color: var(--yk-mist);
  background: rgba(34, 53, 111, .55);
  border-color: var(--yk-hi);
}

@media (min-width: 1000px) {
  .page-about .ab-rail {
    position: sticky;
    top: 96px;
    border-bottom: 0;
    padding-bottom: 0;
  }

  .page-about .ab-rail__list {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .ab-rail__link {
    border-radius: 0 var(--yk-r4) var(--yk-r4) 0;
    border: 0;
    border-left: 2px solid rgba(58, 74, 112, .5);
    background: transparent;
    padding: 9px 14px;
  }

  .page-about .ab-rail__link:hover,
  .page-about .ab-rail__link:focus-visible {
    border-left-color: var(--yk-teal);
    background: rgba(34, 53, 111, .4);
  }
}

/* ---------- 章节通用 ---------- */

.page-about .ab-content {
  min-width: 0;
}

.page-about .ab-chapter {
  scroll-margin-top: 104px;
}

.page-about .ab-chapter + .ab-chapter {
  margin-top: clamp(40px, 6vw, 76px);
  padding-top: clamp(30px, 4vw, 52px);
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-chapter__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 12px;
}

.page-about .ab-chapter__num {
  font-family: var(--yk-font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--yk-teal);
  transition: color .25s var(--yk-ease);
}

.page-about .ab-chapter__title {
  margin: 0;
  font-family: var(--yk-font-head);
  font-weight: 900;
  font-size: clamp(24px, 3.6vw, 38px);
  line-height: 1.08;
  letter-spacing: -.005em;
  color: var(--yk-mist);
}

.page-about .ab-chapter:target .ab-chapter__num {
  color: var(--yk-amber);
}

.page-about .ab-chapter__lede {
  max-width: 60ch;
  margin: 0 0 22px;
  font-size: 16px;
  line-height: 1.68;
  color: var(--yk-haze);
}

.page-about .ab-chapter__note {
  max-width: 62ch;
  margin: 18px 0 0;
  padding-left: 16px;
  border-left: 2px solid var(--yk-teal-deep);
  font-size: 14px;
  line-height: 1.7;
  color: var(--yk-haze);
}

/* ---------- 01 四条主线 ---------- */

.page-about .ab-lanes {
  display: grid;
  gap: 14px;
}

@media (min-width: 720px) {
  .page-about .ab-lanes {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ab-lane--focus {
    grid-column: 1 / -1;
  }
}

.page-about .ab-lane {
  padding: 20px;
  border-radius: var(--yk-r2);
  border: 1px solid var(--ab-line);
  background: var(--ab-panel);
}

.page-about .ab-lane--focus {
  padding: 24px 24px 26px;
  border-color: rgba(55, 245, 193, .42);
  background:
    radial-gradient(90% 130% at 0% 0%, rgba(55, 245, 193, .15), transparent 62%),
    rgba(22, 36, 79, .74);
}

.page-about .ab-lane__tag {
  display: inline-block;
  margin-bottom: 12px;
  padding: 4px 10px;
  border-radius: var(--yk-r4);
  border: 1px solid rgba(55, 245, 193, .35);
  font-family: var(--yk-font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--yk-teal);
}

.page-about .ab-lane--focus .ab-lane__tag {
  border-color: rgba(55, 245, 193, .6);
  background: rgba(55, 245, 193, .1);
}

.page-about .ab-lane__title {
  margin: 0 0 10px;
  font-family: var(--yk-font-head);
  font-weight: 800;
  font-size: clamp(18px, 2.2vw, 22px);
  line-height: 1.3;
  color: var(--yk-mist);
}

.page-about .ab-lane--focus .ab-lane__title {
  font-size: clamp(22px, 3.2vw, 32px);
  line-height: 1.2;
}

.page-about .ab-lane__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--yk-haze);
}

/* ---------- 02 栏目演进 ---------- */

.page-about .ab-path {
  margin-top: 8px;
}

@media (min-width: 880px) {
  .page-about .ab-path {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr);
    gap: clamp(24px, 4vw, 52px);
    align-items: start;
  }
}

.page-about .ab-path__fig {
  margin: 0 0 24px;
  border-radius: var(--yk-r3);
  overflow: hidden;
  border: 1px solid var(--ab-line);
  background: var(--yk-indigo);
}

@media (min-width: 880px) {
  .page-about .ab-path__fig {
    margin: 0;
    position: sticky;
    top: 104px;
  }
}

.page-about .ab-path__fig img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .ab-tl {
  list-style: none;
  margin: 0;
  padding: 0 0 0 26px;
  position: relative;
}

.page-about .ab-tl::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  border-radius: var(--yk-r4);
  background: linear-gradient(180deg, var(--yk-teal) 0%, var(--yk-teal-deep) 46%, rgba(34, 53, 111, .3) 100%);
}

.page-about .ab-tl__item {
  position: relative;
  padding-bottom: 26px;
}

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

.page-about .ab-tl__item::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 6px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--yk-ink);
  border: 2px solid var(--yk-teal);
  box-shadow: 0 0 0 4px rgba(55, 245, 193, .12);
  transition: background .25s var(--yk-ease), box-shadow .25s var(--yk-ease);
}

.page-about .ab-tl__item:hover::before,
.page-about .ab-tl__item:focus-within::before {
  background: var(--yk-teal);
  box-shadow: 0 0 0 7px rgba(55, 245, 193, .2);
}

.page-about .ab-tl__stage {
  display: block;
  margin-bottom: 6px;
  font-family: var(--yk-font-mono);
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--yk-teal-deep);
}

.page-about .ab-tl__title {
  margin: 0 0 6px;
  font-family: var(--yk-font-head);
  font-weight: 800;
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.32;
  color: var(--yk-mist);
}

.page-about .ab-tl__text {
  margin: 0;
  max-width: 54ch;
  font-size: 15px;
  line-height: 1.7;
  color: var(--yk-haze);
}

/* ---------- 03 团队流程 ---------- */

.page-about .ab-facts {
  display: grid;
  gap: 1px;
  margin: 0;
  padding: 0;
  background: var(--ab-line);
  border: 1px solid var(--ab-line);
  border-radius: var(--yk-r2);
  overflow: hidden;
}

@media (min-width: 620px) {
  .page-about .ab-facts {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 940px) {
  .page-about .ab-facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .ab-facts__row {
  display: flex;
  flex-direction: column;
  gap: 7px;
  padding: 18px 20px;
  background: var(--yk-indigo);
}

.page-about .ab-facts__k {
  font-family: var(--yk-font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--yk-haze);
}

.page-about .ab-facts__v {
  margin: 0;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.5;
  color: var(--yk-mist);
}

/* ---------- 04 地区协作 ---------- */

.page-about .ab-region {
  display: grid;
  gap: 22px;
}

@media (min-width: 860px) {
  .page-about .ab-region {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    gap: clamp(24px, 4vw, 48px);
    align-items: center;
  }
}

.page-about .ab-region__fig {
  margin: 0;
  border-radius: var(--yk-r3);
  overflow: hidden;
  border: 1px solid var(--ab-line);
  background: var(--yk-indigo);
}

.page-about .ab-region__fig img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .ab-region__text {
  margin: 0 0 14px;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.72;
  color: var(--yk-haze);
}

.page-about .ab-coop {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .ab-coop li {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 10px 18px;
  border-radius: var(--yk-r4);
  background: rgba(34, 53, 111, .5);
  border: 1px solid var(--ab-line);
  font-size: 14px;
  color: var(--yk-haze);
}

.page-about .ab-coop__num {
  font-family: var(--yk-font-num);
  font-size: 28px;
  font-weight: 800;
  line-height: 1;
  color: var(--yk-amber);
}

.page-about .ab-coop__label {
  font-size: 14px;
}

/* ---------- 05 服务覆盖 ---------- */

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

@media (min-width: 620px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1040px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .ab-stat {
  padding: 22px 20px 24px;
  border-radius: var(--yk-r2);
  border: 1px solid var(--ab-line);
  background: linear-gradient(158deg, rgba(22, 36, 79, .88) 0%, rgba(11, 23, 51, .72) 100%);
}

.page-about .ab-stat__line {
  display: flex;
  align-items: baseline;
  gap: 5px;
}

.page-about .ab-stat__num {
  font-family: var(--yk-font-num);
  font-weight: 800;
  font-size: clamp(38px, 6.5vw, 58px);
  line-height: .95;
  letter-spacing: -.01em;
  color: var(--yk-mist);
}

.page-about .ab-stat__unit {
  font-size: 15px;
  font-weight: 600;
  color: var(--yk-teal);
}

.page-about .ab-stat__label {
  margin: 12px 0 0;
  font-size: 14px;
  line-height: 1.55;
  color: var(--yk-haze);
}

/* ---------- 06 版本迭代 ---------- */

.page-about .ab-vers {
  margin-top: 4px;
}

.page-about .ab-ver {
  border: 1px solid var(--ab-line);
  border-radius: var(--yk-r2);
  background: rgba(11, 23, 51, .62);
  overflow: hidden;
}

.page-about .ab-ver + .ab-ver {
  margin-top: 10px;
}

.page-about .ab-ver[open] {
  border-color: rgba(55, 245, 193, .34);
  background: rgba(16, 28, 62, .78);
}

.page-about .ab-ver__head {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .ab-ver__head::after {
  content: "";
  margin-left: auto;
  flex: none;
  width: 9px;
  height: 9px;
  border-right: 2px solid var(--yk-haze);
  border-bottom: 2px solid var(--yk-haze);
  transform: rotate(45deg) translate(-2px, -2px);
  transition: transform .22s var(--yk-ease), border-color .22s var(--yk-ease);
}

.page-about .ab-ver[open] .ab-ver__head::after {
  transform: rotate(225deg) translate(-2px, -2px);
  border-color: var(--yk-teal);
}

.page-about .ab-ver__tag {
  flex: none;
  font-family: var(--yk-font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--yk-teal);
}

.page-about .ab-ver__name {
  font-size: 15px;
  font-weight: 600;
  line-height: 1.45;
  color: var(--yk-mist);
}

.page-about .ab-ver__text {
  margin: 0;
  padding: 0 18px 18px;
  max-width: 62ch;
  font-size: 14px;
  line-height: 1.72;
  color: var(--yk-haze);
}

/* ---------- 07 资质与备案 ---------- */

.page-about .ab-record {
  margin: 0;
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-record__row {
  display: grid;
  gap: 4px;
  padding: 15px 0;
  border-bottom: 1px solid var(--ab-line);
}

@media (min-width: 620px) {
  .page-about .ab-record__row {
    grid-template-columns: 150px minmax(0, 1fr);
    gap: 20px;
    align-items: baseline;
  }
}

.page-about .ab-record dt {
  font-family: var(--yk-font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--yk-haze);
}

.page-about .ab-record dd {
  margin: 0;
  font-size: 15px;
  line-height: 1.62;
  color: var(--yk-mist);
}

/* ---------- 延伸入口 ---------- */

.page-about .ab-next {
  margin-top: clamp(42px, 6vw, 78px);
  padding-top: clamp(30px, 4vw, 50px);
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-next__title {
  margin: 0;
  font-family: var(--yk-font-head);
  font-weight: 900;
  font-size: clamp(20px, 2.8vw, 28px);
  line-height: 1.2;
  color: var(--yk-mist);
}

.page-about .ab-next__list {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

@media (min-width: 760px) {
  .page-about .ab-next__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.page-about .ab-next__item a {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 16px 18px;
  border-radius: var(--yk-r2);
  border: 1px solid var(--ab-line);
  background: rgba(11, 23, 51, .68);
  text-decoration: none;
  transition: border-color .2s var(--yk-ease), background .2s var(--yk-ease), transform .2s var(--yk-ease);
}

.page-about .ab-next__item a:hover,
.page-about .ab-next__item a:focus-visible {
  border-color: rgba(55, 245, 193, .45);
  background: rgba(22, 36, 79, .78);
  transform: translateY(-2px);
}

.page-about .ab-next__strong {
  font-size: 16px;
  font-weight: 700;
  color: var(--yk-mist);
}

.page-about .ab-next__sub {
  font-size: 13px;
  line-height: 1.55;
  color: var(--yk-haze);
}

/* ---------- 降级 ---------- */

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-rail__link,
  .page-about .ab-tl__item::before,
  .page-about .ab-ver__head::after,
  .page-about .ab-next__item a {
    transition: none;
  }

  .page-about .ab-next__item a:hover,
  .page-about .ab-next__item a:focus-visible {
    transform: none;
  }
}