.page-about {
  --about-rail-w: 7.5rem;
  --about-text: rgba(236, 245, 239, 0.84);
  --about-text-dim: rgba(236, 245, 239, 0.78);
  position: relative;
  padding-bottom: var(--gap-xl);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  margin-top: var(--gap-s);
  padding: clamp(1.5rem, 4vw, 2.9rem) 0 clamp(1.4rem, 3.4vw, 2.3rem);
  border-top: var(--rule);
  border-bottom: var(--rule);
  background: linear-gradient(180deg, rgba(20, 50, 40, 0.62) 0%, rgba(6, 20, 15, 0) 100%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 9px;
  pointer-events: none;
  background-image: repeating-linear-gradient(
    to right,
    var(--line-blue) 0 1px,
    transparent 1px 6.25%
  );
  background-size: 100% 100%;
  background-repeat: no-repeat;
  opacity: 0.7;
}

.page-about .about-code {
  margin: 0 0 var(--gap-s);
  font-family: var(--font-data);
  font-size: 12px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--neon);
}

.page-about .about-hero h1 {
  margin: 0;
  max-width: 18em;
  font-family: var(--font-title);
  font-weight: 700;
  font-size: clamp(30px, 4.4vw, 54px);
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--chalk);
}

.page-about .about-lede {
  margin: var(--gap-m) 0 0;
  max-width: 42em;
  font-size: clamp(15px, 1.25vw, 17px);
  line-height: 1.85;
  color: var(--mist);
}

.page-about .about-toc {
  display: flex;
  flex-wrap: wrap;
  gap: var(--gap-xs);
  margin-top: var(--gap-m);
}

.page-about .about-toc__link {
  display: inline-flex;
  align-items: baseline;
  gap: 0.45rem;
  padding: 0.34rem 0.72rem;
  border: 1px solid var(--line-blue);
  border-radius: var(--r-pill);
  font-size: 13px;
  color: var(--mist);
  text-decoration: none;
  transition: border-color var(--dur) var(--ease), color var(--dur) var(--ease),
    background-color var(--dur) var(--ease);
}

.page-about .about-toc__link span {
  font-family: var(--font-num);
  font-size: 11px;
  color: var(--line-blue);
  transition: color var(--dur) var(--ease);
}

.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  color: var(--chalk);
  border-color: var(--neon);
  background: rgba(20, 50, 40, 0.6);
}

.page-about .about-toc__link:hover span,
.page-about .about-toc__link:focus-visible span {
  color: var(--neon);
}

/* ---------- 首屏下方：左图 + 右数据 ---------- */

.page-about .about-media {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--gap-m);
  margin-top: var(--gap-l);
}

.page-about .about-media__figure {
  margin: 0;
}

.page-about .image-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--r-m);
}

.page-about .about-media__side {
  border-top: 1px solid var(--line-blue);
  padding-top: var(--gap-m);
}

.page-about .about-facts {
  margin: var(--gap-s) 0 0;
  display: grid;
  gap: 0.6rem;
}

.page-about .about-facts__item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--gap-s);
  padding-bottom: 0.5rem;
  border-bottom: 1px dashed var(--line-blue);
}

.page-about .about-facts__item dt {
  order: 2;
  font-size: 13px;
  color: var(--mist);
}

.page-about .about-facts__item dd {
  order: 1;
  margin: 0;
  font-family: var(--font-num);
  font-size: clamp(20px, 2.6vw, 27px);
  line-height: 1;
  color: var(--neon);
}

.page-about .about-facts__num {
  font-family: inherit;
}

.page-about .about-media__note {
  margin: var(--gap-s) 0 0;
  font-size: 12.5px;
  line-height: 1.75;
  color: var(--mist);
}

/* ---------- 章节骨架 ---------- */

.page-about .about-section {
  position: relative;
  padding: clamp(2rem, 5vw, 3.2rem) 0;
  border-top: var(--rule);
  scroll-margin-top: 5.5rem;
}

.page-about .about-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--gap-m);
}

.page-about .about-rail {
  display: flex;
  align-items: baseline;
  gap: var(--gap-s);
}

.page-about .about-rail__num {
  font-family: var(--font-num);
  font-size: clamp(22px, 2.8vw, 32px);
  line-height: 1;
  color: var(--line-blue);
  transition: color var(--dur) var(--ease);
}

.page-about .about-rail__label {
  font-family: var(--font-data);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--mist);
}

.page-about .about-section:target .about-rail__num {
  color: var(--neon);
}

/* ---------- 章节标题与正文 ---------- */

.page-about .about-h2 {
  position: relative;
  margin: 0 0 var(--gap-m);
  padding-bottom: 0.7rem;
  font-family: var(--font-title);
  font-size: clamp(21px, 2.5vw, 28px);
  font-weight: 700;
  line-height: 1.36;
  letter-spacing: -0.005em;
  color: var(--chalk);
}

.page-about .about-h2::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 6rem;
  height: 2px;
  background: var(--line-blue);
  transform: scaleX(0.35);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-section:target .about-h2::after {
  transform: scaleX(1);
  background: var(--neon);
}

.page-about .about-body p {
  margin: 0 0 var(--gap-m);
  max-width: 42em;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--about-text);
}

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

.page-about .about-body__lede {
  max-width: 42em;
  padding-left: var(--gap-s);
  border-left: 2px solid var(--line-blue);
  color: var(--mist);
}

.page-about .about-body__note {
  padding: var(--gap-s) 0 var(--gap-s) var(--gap-m);
  border-left: 2px solid var(--line-blue);
  font-size: 14px;
  color: var(--mist);
}

.page-about .about-body__note a {
  color: var(--neon);
  text-decoration: none;
  border-bottom: 1px dashed rgba(70, 227, 164, 0.5);
  transition: border-color var(--dur) var(--ease);
}

.page-about .about-body__note a:hover,
.page-about .about-body__note a:focus-visible {
  border-bottom-color: var(--neon);
}

/* ---------- 刻度尺 ---------- */

.page-about .about-scale {
  height: 22px;
  margin-bottom: var(--gap-m);
  border-bottom: 1px solid var(--line-blue);
  background-image: repeating-linear-gradient(
    to right,
    var(--line-blue) 0 1px,
    transparent 1px 6.25%
  );
  background-size: 100% 8px;
  background-repeat: no-repeat;
  background-position: 0 100%;
  opacity: 0.8;
}

/* ---------- 时间轴 ---------- */

.page-about .about-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--gap-m);
}

.page-about .about-timeline__item {
  display: grid;
  grid-template-columns: 1.5rem minmax(0, 1fr);
  gap: 0 var(--gap-s);
}

.page-about .about-timeline__marker {
  position: relative;
  display: flex;
  justify-content: center;
}

.page-about .about-timeline__marker::before {
  content: "";
  position: absolute;
  top: 1.4rem;
  bottom: calc(-1 * var(--gap-m));
  width: 1px;
  background: var(--line-blue);
}

.page-about .about-timeline__item:last-child .about-timeline__marker::before {
  display: none;
}

.page-about .about-timeline__dot {
  margin-top: 0.45rem;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  border: 1px solid var(--line-blue);
  background: var(--ink-deep);
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease),
    box-shadow var(--dur) var(--ease);
}

.page-about .about-timeline__item:hover .about-timeline__dot {
  border-color: var(--neon);
  background: var(--neon);
  box-shadow: 0 0 0 4px rgba(70, 227, 164, 0.14);
}

.page-about .about-timeline__meta {
  display: flex;
  align-items: center;
  gap: var(--gap-s);
  margin: 0 0 0.35rem;
}

.page-about .about-timeline__year {
  font-family: var(--font-num);
  font-size: 14.5px;
  letter-spacing: 0.04em;
  color: var(--mist);
}

.page-about .about-timeline__title {
  margin: 0 0 0.4rem;
  font-family: var(--font-title);
  font-size: 17.5px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--chalk);
}

.page-about .about-timeline__desc {
  margin: 0;
  max-width: 40em;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--about-text-dim);
}

.page-about .about-timeline__more {
  margin: 0.5rem 0 0;
  padding-left: var(--gap-s);
  border-left: 2px solid var(--line-blue);
  font-size: 13.5px;
  line-height: 1.75;
  color: var(--mist);
  overflow: hidden;
  max-height: 8em;
  opacity: 1;
  transition: max-height 220ms var(--ease), opacity 220ms var(--ease), transform 220ms var(--ease);
}

/* ---------- 团队折叠 ---------- */

.page-about .about-team {
  margin: var(--gap-m) 0 var(--gap-l);
}

.page-about .about-role {
  border: 1px solid var(--line-blue);
  border-radius: var(--r-m);
  background: rgba(11, 14, 12, 0.66);
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-role + .about-role {
  margin-top: 0.6rem;
}

.page-about .about-role:hover {
  border-color: rgba(70, 227, 164, 0.42);
}

.page-about .about-role[open] {
  border-color: rgba(70, 227, 164, 0.55);
  background: rgba(20, 50, 40, 0.5);
}

.page-about .about-role__summary {
  display: flex;
  align-items: baseline;
  gap: var(--gap-s);
  padding: 0.85rem 1.05rem;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-data);
  font-size: 15px;
  letter-spacing: 0.1em;
  color: var(--chalk);
}

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

.page-about .about-role__summary::after {
  content: "+";
  font-family: var(--font-num);
  font-size: 15px;
  line-height: 1;
  color: var(--line-blue);
  transition: color var(--dur) var(--ease);
}

.page-about .about-role[open] .about-role__summary::after {
  content: "–";
  color: var(--neon);
}

.page-about .about-role__count {
  margin-left: auto;
  font-family: var(--font-num);
  font-size: 14px;
  letter-spacing: 0;
  color: var(--neon);
}

.page-about .about-role__body {
  padding: 0.85rem 1.05rem 1rem;
  border-top: 1px dashed var(--line-blue);
}

.page-about .about-role__body p {
  margin: 0;
  max-width: 40em;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--about-text-dim);
}

.page-about .about-team__figure {
  margin: 0;
}

/* ---------- 数据来源 ---------- */

.page-about .about-source__band {
  margin: var(--gap-m) 0;
}

.page-about .about-cadence {
  list-style: none;
  margin: 0 0 var(--gap-m);
  padding: 0;
}

.page-about .about-cadence li {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.35rem;
  padding: 0.7rem 0;
  border-bottom: 1px dashed var(--line-blue);
}

.page-about .about-cadence li:first-child {
  border-top: 1px dashed var(--line-blue);
}

.page-about .about-cadence p {
  margin: 0;
  max-width: 40em;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--about-text-dim);
}

.page-about .about-source__figure {
  margin: var(--gap-l) 0 0;
}

/* ---------- 四个页面形态 ---------- */

.page-about .about-shapes {
  list-style: none;
  margin: var(--gap-m) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .about-shapes__item {
  display: grid;
  grid-template-columns: 1.6rem minmax(0, 1fr);
  gap: 0 var(--gap-s);
  padding: var(--gap-m) 0;
  border-top: 1px solid var(--line-blue);
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-shapes__item:last-child {
  border-bottom: 1px solid var(--line-blue);
}

.page-about .about-shapes__item:hover {
  border-top-color: var(--neon);
  background: rgba(20, 50, 40, 0.34);
}

.page-about .about-shapes__no {
  font-family: var(--font-data);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--neon);
  padding-top: 0.15rem;
}

.page-about .about-shapes__text h3 {
  margin: 0 0 0.35rem;
  font-family: var(--font-title);
  font-size: 17px;
  font-weight: 700;
  line-height: 1.4;
  color: var(--chalk);
}

.page-about .about-shapes__text p {
  margin: 0 0 0.55rem;
  max-width: 38em;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--about-text-dim);
}

.page-about .about-shapes__text .link-arrow {
  font-size: 13.5px;
}

/* ---------- 边界：在意 / 不做 ---------- */

.page-about .about-scope {
  display: grid;
  gap: var(--gap-m);
  margin-top: var(--gap-m);
}

.page-about .about-scope__col {
  padding: var(--gap-m);
  border: 1px solid var(--line-blue);
  border-radius: var(--r-m);
}

.page-about .about-scope__col--do {
  background: rgba(20, 50, 40, 0.5);
  border-top: 2px solid var(--neon);
}

.page-about .about-scope__col--dont {
  background: rgba(11, 14, 12, 0.72);
  border-top: 2px solid var(--amber);
}

.page-about .about-scope__title {
  margin: 0 0 var(--gap-s);
  font-family: var(--font-data);
  font-size: 15px;
  letter-spacing: 0.18em;
  color: var(--chalk);
}

.page-about .about-scope__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.7rem;
}

.page-about .about-scope__list li {
  position: relative;
  padding-left: 1.15rem;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--about-text);
}

.page-about .about-scope__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62rem;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--line-blue);
}

.page-about .about-scope__col--do .about-scope__list li::before {
  background: var(--neon);
}

.page-about .about-scope__col--dont .about-scope__list li::before {
  background: var(--amber);
}

/* ---------- 收尾索引 ---------- */

.page-about .about-index {
  margin-top: var(--gap-l);
  padding: var(--gap-l) var(--gap-m);
  border: 1px solid var(--line-blue);
  border-radius: var(--r-l);
  background: rgba(20, 50, 40, 0.42);
}

.page-about .about-index__list {
  list-style: none;
  margin: var(--gap-s) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-blue);
  border: 1px solid var(--line-blue);
  border-radius: var(--r-s);
  overflow: hidden;
}

.page-about .about-index__list li {
  background: var(--ink-deep);
}

.page-about .about-index__list a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--gap-s);
  padding: 0.85rem 1rem;
  font-size: 14.5px;
  color: var(--chalk);
  text-decoration: none;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .about-index__list a:hover,
.page-about .about-index__list a:focus-visible {
  background: var(--ink-turf);
  color: var(--neon);
}

.page-about .about-index__arrow {
  font-family: var(--font-num);
  color: var(--line-blue);
  transition: transform var(--dur) var(--ease), color var(--dur) var(--ease);
}

.page-about .about-index__list a:hover .about-index__arrow,
.page-about .about-index__list a:focus-visible .about-index__arrow {
  color: var(--neon);
  transform: translateX(3px);
}

.page-about .about-index__note {
  margin: var(--gap-m) 0 0;
  padding-top: var(--gap-s);
  border-top: 1px dashed var(--line-blue);
  font-size: 12.5px;
  line-height: 1.8;
  color: var(--mist);
}

/* ---------- 键盘焦点 ---------- */

.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--neon);
  outline-offset: 2px;
  border-radius: var(--r-s);
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .about-cadence li {
    grid-template-columns: 6.5rem minmax(0, 1fr);
    gap: var(--gap-s);
    align-items: baseline;
  }

  .page-about .about-index__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-media__side {
    border-top: 0;
    border-left: 1px solid var(--line-blue);
    padding-top: 0;
    padding-left: var(--gap-m);
  }
}

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

@media (min-width: 900px) {
  .page-about .about-grid {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: var(--gap-l);
  }

  .page-about .about-rail {
    display: block;
    position: sticky;
    top: 6.5rem;
    align-self: start;
  }

  .page-about .about-rail__label {
    display: block;
    margin-top: 0.45rem;
  }

  .page-about .about-media {
    grid-template-columns: minmax(0, 8fr) minmax(0, 4fr);
    gap: var(--gap-l);
    align-items: end;
  }

  .page-about .about-shapes {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: var(--gap-l);
  }

  .page-about .about-shapes__item:last-child {
    border-bottom: 0;
  }
}

@media (hover: hover) and (min-width: 900px) {
  .page-about .about-timeline__more {
    max-height: 0;
    opacity: 0;
    transform: translateY(-3px);
  }

  .page-about .about-timeline__item:hover .about-timeline__more {
    max-height: 8em;
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition-duration: 1ms !important;
    animation-duration: 1ms !important;
  }
}
</main>