.page-about {
  --about-line: rgba(22, 59, 53, 0.85);
  display: block;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-body);
  overflow-x: clip;
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-family: var(--font-display);
  font-weight: 900;
  text-wrap: balance;
}

.page-about h1 {
  font-size: clamp(32px, 7.2vw, 56px);
  line-height: 1.02;
  letter-spacing: -0.02em;
  margin: 0;
}

.page-about h2 {
  font-size: clamp(25px, 4.6vw, 36px);
  line-height: 1.12;
  letter-spacing: -0.01em;
  margin: 0;
}

.page-about h3 {
  font-size: 18px;
  line-height: 1.3;
  margin: 0;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding: 22px 0 52px;
  border-bottom: 1px solid var(--grid);
  background:
    radial-gradient(130% 100% at 92% 0%, rgba(56, 242, 196, 0.14), transparent 60%),
    linear-gradient(180deg, var(--stand) 0%, var(--ink) 82%);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background-image:
    linear-gradient(to right, var(--about-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--about-line) 1px, transparent 1px);
  background-size: 72px 72px;
  opacity: 0.26;
  pointer-events: none;
}

.page-about .crumb {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--mist);
}

.page-about .crumb a {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 180ms var(--ease), border-color 180ms var(--ease);
}

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

.page-about .crumb__sep {
  margin: 0 8px;
  color: var(--grid);
}

.page-about .about-hero__grid {
  display: grid;
  gap: 30px;
  padding-top: 26px;
}

.page-about .about-hero__intro {
  margin: 18px 0 0;
  max-width: 48ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .about-hero__tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 22px 0 0;
  padding: 0;
}

.page-about .about-hero__tags li {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--mist);
  border: 1px solid var(--grid);
  background: rgba(5, 15, 13, 0.55);
  padding: 5px 10px;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .media-frame {
  position: relative;
  margin: 0;
  overflow: hidden;
  border: 2px solid var(--grid);
  background:
    repeating-linear-gradient(135deg, rgba(56, 242, 196, 0.05) 0 8px, transparent 8px 16px),
    var(--stand-soft);
  box-shadow: var(--shadow-hard);
}

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

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

/* ---------- 起点 ---------- */

.page-about .about-origin {
  padding: 54px 0;
  border-bottom: 1px solid var(--grid);
}

.page-about .about-origin__grid {
  display: grid;
  gap: 34px;
}

.page-about .about-origin__main h2 {
  margin-top: 12px;
}

.page-about .about-origin__prose {
  margin-top: 20px;
  color: var(--mist);
}

.page-about .about-origin__prose p {
  margin: 0 0 16px;
  font-size: 15.5px;
  line-height: 1.85;
}

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

.page-about .about-origin__side {
  display: grid;
  gap: 18px;
  align-content: start;
  padding-top: 6px;
}

.page-about .about-fact {
  display: grid;
  gap: 4px;
  padding-left: 16px;
  border-left: 2px solid var(--grid);
}

.page-about .about-fact__num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 26px;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--cyan);
}

.page-about .about-fact__text {
  font-size: 13.5px;
  line-height: 1.65;
  color: var(--mist);
}

/* ---------- 三层校验 ---------- */

.page-about .about-check {
  padding: 54px 0;
  border-bottom: 1px solid var(--grid);
  background:
    linear-gradient(180deg, rgba(36, 26, 61, 0.55), rgba(5, 15, 13, 0) 68%),
    var(--ink);
}

.page-about .about-head__lead {
  margin: 14px 0 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist);
}

.page-about .check-list {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  position: relative;
  border-left: 2px solid var(--grid);
}

.page-about .check-step {
  position: relative;
  padding-left: 26px;
}

.page-about .check-step::before {
  content: "";
  position: absolute;
  left: -9px;
  top: 24px;
  width: 16px;
  height: 16px;
  box-sizing: border-box;
  background: var(--ink);
  border: 2px solid var(--cyan);
  transform: rotate(45deg);
}

.page-about .check-step__h {
  margin: 0;
  font-family: inherit;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
}

.page-about .check-step__trigger {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: baseline;
  gap: 12px;
  width: 100%;
  padding: 18px 0 15px;
  background: none;
  border: 0;
  border-top: 1px solid var(--grid);
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: color 180ms var(--ease);
}

.page-about .check-step:first-child .check-step__trigger {
  border-top: 0;
}

.page-about .check-step__trigger:hover,
.page-about .check-step__trigger:focus-visible {
  color: var(--cyan);
}

.page-about .expand__index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--cyan);
}

.page-about .expand__label {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 20px;
  letter-spacing: 0.01em;
}

.page-about .expand__sign {
  font-family: var(--font-mono);
  font-size: 20px;
  line-height: 1;
  color: var(--cyan);
  transition: transform 200ms var(--ease);
}

.page-about .expand__trigger[aria-expanded="true"] .expand__sign {
  transform: rotate(45deg);
}

.page-about .expand__panel {
  padding: 0 0 20px;
}

.page-about .expand__body {
  padding-left: 14px;
  border-left: 2px solid var(--cyan);
  max-width: 62ch;
}

.page-about .expand__body p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--mist);
}

/* ---------- 覆盖与归档 ---------- */

.page-about .about-coverage {
  padding: 54px 0;
  border-bottom: 1px solid var(--grid);
}

.page-about .about-stats {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px;
  background: var(--grid);
  border: 2px solid var(--grid);
  box-shadow: var(--shadow-hard);
}

.page-about .about-stat {
  background: var(--stand);
  padding: 20px 16px 22px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .about-stat .stat__num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(28px, 5.4vw, 42px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--cyan);
}

.page-about .about-stat .stat__label {
  font-size: 13px;
  line-height: 1.55;
  color: var(--mist);
}

.page-about .about-coverage__body {
  display: grid;
  gap: 30px;
  margin-top: 32px;
}

.page-about .about-coverage__list {
  display: grid;
  gap: 2px;
  background: var(--grid);
  border: 2px solid var(--grid);
}

.page-about .cov-item {
  background: var(--stand-soft);
}

.page-about .cov-item__h {
  margin: 0;
  font-family: inherit;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
}

.page-about .cov-item__trigger {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: baseline;
  gap: 12px;
  width: 100%;
  padding: 16px 18px;
  background: none;
  border: 0;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: color 180ms var(--ease);
}

.page-about .cov-item__trigger:hover,
.page-about .cov-item__trigger:focus-visible {
  color: var(--cyan);
}

.page-about .cov-item .expand__label {
  font-size: 18px;
}

.page-about .cov-item .expand__panel {
  padding: 0 18px 18px;
}

.page-about .about-coverage__media {
  border-color: var(--grid);
}

/* ---------- 看台之外 ---------- */

.page-about .about-service {
  padding: 54px 0;
  border-bottom: 1px solid var(--grid);
  background: var(--ink);
}

.page-about .about-service__list {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
  background: var(--grid);
  border: 2px solid var(--grid);
}

.page-about .service-item {
  background: var(--stand);
  padding: 22px 20px 24px;
}

.page-about .service-item__num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1;
  letter-spacing: 0.14em;
  color: var(--ref);
  border: 1px solid var(--ref);
  padding: 4px 7px;
  margin-bottom: 14px;
}

.page-about .service-item h3 {
  color: var(--paper);
}

.page-about .service-item p {
  margin: 10px 0 0;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--mist);
}

/* ---------- 里程碑 ---------- */

.page-about .about-timeline {
  padding: 54px 0;
  border-bottom: 1px solid var(--grid);
  background:
    linear-gradient(180deg, rgba(61, 23, 34, 0.32), rgba(5, 15, 13, 0) 62%),
    var(--ink);
}

.page-about .timeline {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
  background: var(--grid);
  border: 2px solid var(--grid);
}

.page-about .tl-node {
  background: var(--stand-soft);
}

.page-about .tl-node--hot {
  background: var(--wine);
}

.page-about .tl-node__h {
  margin: 0;
  font-family: inherit;
  font-size: inherit;
  font-weight: inherit;
  line-height: inherit;
}

.page-about .tl-node__trigger {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-areas:
    "year sign"
    "title title";
  align-items: baseline;
  gap: 6px 12px;
  width: 100%;
  padding: 20px 18px 18px;
  background: none;
  border: 0;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: color 180ms var(--ease);
}

.page-about .tl-node__trigger:hover,
.page-about .tl-node__trigger:focus-visible {
  color: var(--cyan);
}

.page-about .tl-node__year {
  grid-area: year;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(26px, 5.2vw, 34px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--cyan);
}

.page-about .tl-node--hot .tl-node__year {
  color: var(--ref);
}

.page-about .tl-node__title {
  grid-area: title;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: 17px;
  line-height: 1.35;
  letter-spacing: 0.01em;
}

.page-about .tl-node__trigger .expand__sign {
  grid-area: sign;
}

.page-about .tl-node .expand__panel {
  padding: 0 18px 20px;
}

.page-about .tl-node .expand__body {
  border-left-color: var(--ref);
}

/* ---------- 结尾 ---------- */

.page-about .about-cta {
  padding: 52px 0 60px;
  background: linear-gradient(180deg, var(--ink), var(--stand-soft));
}

.page-about .about-cta__inner {
  display: grid;
  gap: 24px;
  align-items: center;
  padding: 26px 22px;
  border: 2px solid var(--grid);
  background: rgba(10, 36, 32, 0.72);
  box-shadow: var(--shadow-hard);
}

.page-about .about-cta__text h2 {
  margin-top: 10px;
}

.page-about .about-cta__text p:last-child {
  margin: 14px 0 0;
  max-width: 56ch;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--mist);
}

.page-about .about-cta .btn {
  justify-self: start;
}

/* ---------- 断点 ---------- */

@media (min-width: 700px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

@media (min-width: 900px) {
  .page-about .about-hero {
    padding: 26px 0 66px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: 52px;
    align-items: end;
    padding-top: 44px;
  }

  .page-about .about-origin,
  .page-about .about-check,
  .page-about .about-coverage,
  .page-about .about-service,
  .page-about .about-timeline {
    padding: 72px 0;
  }

  .page-about .about-origin__grid {
    grid-template-columns: minmax(0, 1fr) 272px;
    gap: 56px;
  }

  .page-about .about-origin__side {
    gap: 24px;
    padding-top: 12px;
  }

  .page-about .about-check__grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .about-coverage__body {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: 44px;
    align-items: start;
  }

  .page-about .about-coverage__media {
    transform: translateY(-10px);
  }

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

  .page-about .about-cta__inner {
    grid-template-columns: minmax(0, 1fr) auto;
    padding: 36px 40px;
    gap: 36px;
  }

  .page-about .about-cta .btn {
    justify-self: end;
  }
}

@media (min-width: 1120px) {
  .page-about .about-hero__intro {
    font-size: 17px;
  }

  .page-about .about-origin__prose p {
    font-size: 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .expand__sign,
  .page-about .check-step__trigger,
  .page-about .cov-item__trigger,
  .page-about .tl-node__trigger,
  .page-about .crumb a {
    transition: none;
  }
}