.page-about {
  --page-gap-lg: clamp(4rem, 9vw, 7.5rem);
  --page-gap-md: clamp(2.5rem, 5vw, 4.2rem);
  --line: rgba(18, 58, 102, .18);
  --line-dark: rgba(245, 247, 250, .16);
  --paper-deep: #eef2f7;
  background: var(--paper);
  color: var(--ink);
}

/* ===== 首屏海报 ===== */
.page-about__hero {
  position: relative;
  background: linear-gradient(152deg, var(--ink) 0%, #071a33 34%, var(--ocean) 78%, #0a2b52 100%);
  color: var(--paper);
  padding: 3rem 0 4rem;
  overflow: hidden;
}

.page-about__hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(-55deg, rgba(255, 255, 255, .03) 0 1px, transparent 1px 9px);
  pointer-events: none;
}

.page-about__hero::after {
  content: "30s";
  position: absolute;
  right: -0.12em;
  bottom: -0.28em;
  font-family: var(--font-mono);
  font-size: clamp(6rem, 17vw, 13rem);
  font-weight: 800;
  color: rgba(255, 255, 255, .04);
  line-height: 1;
  pointer-events: none;
  letter-spacing: -.06em;
}

.page-about__hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 2rem;
  align-items: center;
}

.page-about__hero-copy .site-breadcrumbs {
  margin-bottom: 1.4rem;
  font-size: .85rem;
}

.page-about__hero-copy .site-breadcrumbs a {
  color: var(--pulse);
  text-decoration: none;
}

.page-about__hero-copy .site-breadcrumbs a:hover {
  color: var(--orange);
}

.page-about__hero-copy .site-breadcrumbs [aria-current="page"] {
  color: rgba(245, 247, 250, .68);
}

.page-about__kicker {
  display: flex;
  align-items: center;
  font-family: var(--font-mono);
  font-size: .8rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: rgba(245, 247, 250, .82);
  margin: 0 0 1rem;
}

.page-about__kicker-en {
  color: var(--pulse);
  font-weight: 700;
}

.page-about__kicker-divider {
  color: var(--orange);
  margin: 0 .55rem;
  letter-spacing: 0;
}

.page-about__hero-title {
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: clamp(1.85rem, 4.8vw, 3.5rem);
  line-height: 1.14;
  letter-spacing: -.02em;
  transform: skewX(-3deg);
  text-wrap: balance;
  margin: 0 0 1.1rem;
  max-width: 12em;
}

.page-about__hero-lead {
  font-size: 1rem;
  line-height: 1.72;
  color: rgba(245, 247, 250, .82);
  max-width: 38em;
  margin: 0 0 1.8rem;
}

.page-about__hero-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: .8rem;
  max-width: 580px;
}

.page-about__hero-stat {
  border: 1px solid var(--line-dark);
  border-radius: var(--radius);
  padding: 1rem 1.05rem;
  background: rgba(11, 30, 58, .42);
  transition: border-color .25s ease, transform .25s ease;
}

.page-about__hero-stat:hover {
  border-color: rgba(255, 106, 0, .7);
  transform: translateY(-2px);
}

.page-about__hero-stat-num {
  font-family: var(--font-mono);
  font-size: 1.7rem;
  font-weight: 800;
  color: var(--pulse);
  line-height: 1.15;
  display: block;
}

.page-about__hero-stat-unit {
  font-size: .6em;
  font-weight: 500;
  color: var(--orange);
  margin-left: .12em;
}

.page-about__hero-stat-label {
  display: block;
  font-size: .8rem;
  color: rgba(245, 247, 250, .68);
  margin-top: .35rem;
}

.page-about__hero-figure {
  position: relative;
  margin: 0;
}

.page-about__hero-img {
  width: 100%;
  height: auto;
  border-radius: var(--radius);
  border: 1px solid var(--line-dark);
  box-shadow: var(--shadow);
  transform: rotate(1.3deg);
  display: block;
}

.page-about__hero-figure figcaption {
  margin-top: .8rem;
  font-size: .78rem;
  color: rgba(245, 247, 250, .6);
  font-family: var(--font-mono);
  letter-spacing: .04em;
  text-align: right;
}

/* ===== 通用章节节奏 ===== */
.page-about__section {
  padding: var(--page-gap-lg) 0;
  position: relative;
}

.page-about__section--paper {
  background: linear-gradient(180deg, var(--paper) 0%, var(--paper-deep) 100%);
  color: var(--ink);
}

.page-about__section--ink {
  background: linear-gradient(145deg, var(--ink) 0%, #081b33 55%, var(--ocean) 130%);
  color: var(--paper);
}

.page-about__section--slate {
  background: radial-gradient(circle at 15% 20%, rgba(123, 97, 255, .28) 0, transparent 32%), radial-gradient(circle at 85% 70%, rgba(57, 255, 136, .14) 0, transparent 38%), var(--slate);
  color: var(--paper);
}

.page-about__section-head {
  max-width: 780px;
  margin-bottom: var(--page-gap-md);
}

.page-about__section-kicker {
  display: flex;
  align-items: center;
  gap: .5rem;
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--orange);
  margin: 0 0 .7rem;
}

.page-about__section-kicker::after {
  content: "";
  height: 1px;
  flex: 1;
  background: linear-gradient(90deg, currentColor, transparent);
  opacity: .45;
}

.page-about__section-kicker-en {
  font-weight: 800;
}

.page-about__section-title {
  font-family: var(--font-heading);
  font-size: clamp(1.7rem, 3.2vw, 2.5rem);
  font-weight: 900;
  transform: skewX(-3deg);
  letter-spacing: -.01em;
  margin: 0 0 .8rem;
  text-wrap: balance;
}

.page-about__section-desc {
  font-size: 1.04rem;
  line-height: 1.68;
  color: inherit;
  opacity: .82;
  margin: 0;
}

.page-about__section-head--on-dark .page-about__section-kicker {
  color: var(--pulse);
}

.page-about__section-head--on-dark .page-about__section-desc {
  color: rgba(245, 247, 250, .78);
}

/* ===== 时间线 ===== */
.page-about__timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
  display: grid;
  gap: 2rem;
}

.page-about__timeline::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 16px;
  width: 2px;
  background: linear-gradient(180deg, var(--orange), var(--pulse) 55%, var(--violet));
  opacity: .38;
}

.page-about__timeline-item {
  position: relative;
  padding-left: 3.5rem;
}

.page-about__timeline-dot {
  position: absolute;
  left: 9px;
  top: 1.5rem;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--pulse);
  border: 3px solid var(--ink);
  box-shadow: 0 0 0 3px rgba(57, 255, 136, .28), 0 0 18px rgba(57, 255, 136, .75);
  z-index: 1;
}

.page-about__timeline-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.3rem 1.35rem;
  box-shadow: 0 10px 22px rgba(3, 10, 22, .09);
  transition: transform .25s ease, box-shadow .25s ease, border-color .25s ease;
}

.page-about__timeline-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 16px 30px rgba(3, 10, 22, .14);
  border-color: rgba(255, 106, 0, .42);
}

.page-about__timeline-era {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .14em;
  color: var(--orange);
  text-transform: uppercase;
  font-weight: 700;
  margin: 0 0 .5rem;
}

.page-about__timeline-card-title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 800;
  margin: 0 0 .6rem;
  line-height: 1.32;
}

.page-about__timeline-card-text {
  font-size: .95rem;
  line-height: 1.68;
  color: rgba(11, 30, 58, .8);
  margin: 0;
}

.page-about__timeline-more {
  border-top: 1px dashed rgba(18, 58, 102, .25);
  margin-top: .9rem;
  padding-top: .55rem;
}

.page-about__timeline-more summary {
  font-family: var(--font-mono);
  font-size: .8rem;
  font-weight: 700;
  cursor: pointer;
  color: var(--orange);
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  padding: .2rem 0;
  transition: color .2s ease;
}

.page-about__timeline-more summary:hover {
  color: var(--ink);
}

.page-about__timeline-more summary::-webkit-details-marker {
  display: none;
}

.page-about__timeline-more summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1.1rem;
  line-height: 1;
  color: var(--pulse);
}

.page-about__timeline-more[open] summary::after {
  content: "–";
  color: var(--orange);
}

.page-about__timeline-more-body {
  padding-top: .6rem;
  font-size: .92rem;
  line-height: 1.66;
  color: rgba(11, 30, 58, .76);
}

.page-about__timeline-more-body p {
  margin: 0;
}

.page-about__timeline-cta {
  margin-top: 2.6rem;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.page-about__timeline-cta .site-btn--ghost {
  border-color: var(--ocean);
  color: var(--ocean);
}

/* ===== 数据工程层叠剖面 ===== */
.page-about__eng-stack {
  display: grid;
  gap: 1.1rem;
}

.page-about__eng-layer {
  position: relative;
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  background: rgba(18, 58, 102, .62);
  border: 1px solid var(--line-dark);
  border-radius: var(--radius);
  padding: 1.3rem 1.4rem;
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: transform .3s ease, border-color .3s ease;
}

.page-about__eng-layer::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: repeating-linear-gradient(-48deg, rgba(255, 255, 255, .025) 0 10px, transparent 10px 20px);
  pointer-events: none;
}

.page-about__eng-layer:hover {
  border-color: rgba(57, 255, 136, .55);
}

.page-about__eng-layer-num {
  font-family: var(--font-mono);
  font-size: 1.7rem;
  font-weight: 800;
  color: var(--pulse);
  line-height: 1;
  min-width: 2.2ch;
  position: relative;
  z-index: 1;
}

.page-about__eng-layer-content {
  position: relative;
  z-index: 1;
  flex: 1;
}

.page-about__eng-layer-title {
  font-family: var(--font-heading);
  font-size: 1.08rem;
  font-weight: 800;
  color: var(--paper);
  margin: 0 0 .35rem;
}

.page-about__eng-layer-text {
  font-size: .92rem;
  line-height: 1.66;
  color: rgba(245, 247, 250, .74);
  margin: 0;
  max-width: 38em;
}

.page-about__eng-tag {
  align-self: center;
  margin-left: .4rem;
  font-family: var(--font-mono);
  font-size: .62rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  border: 1px solid rgba(57, 255, 136, .42);
  color: var(--pulse);
  padding: .35em .75em;
  border-radius: 999px;
  white-space: nowrap;
  display: none;
  flex-shrink: 0;
}

.page-about__eng-terminal {
  margin-top: 1.6rem;
  background: rgba(3, 10, 22, .85);
  border: 1px solid rgba(57, 255, 136, .35);
  border-radius: var(--radius);
  padding: 1.2rem 1.4rem;
  font-family: var(--font-mono);
  font-size: .92rem;
  color: var(--paper);
  line-height: 1.8;
  box-shadow: var(--shadow);
  position: relative;
  overflow: hidden;
}

.page-about__eng-terminal::before {
  content: "";
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(0deg, transparent 0 34px, rgba(57, 255, 136, .06) 34px 36px);
  pointer-events: none;
}

.page-about__terminal-line {
  margin: 0;
  display: flex;
  align-items: center;
  gap: .5rem;
}

.page-about__terminal-line::before {
  content: ">";
  color: var(--pulse);
}

.page-about__terminal-strong {
  font-weight: 800;
  font-size: .8rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--orange);
  margin-bottom: .3rem;
}

.page-about__terminal-strong::before {
  content: "#";
  color: var(--orange);
}

.page-about__terminal-ok {
  color: var(--pulse);
  margin-top: .3rem;
}

.page-about__pulse-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--pulse);
  box-shadow: 0 0 10px var(--pulse);
  display: inline-block;
  flex-shrink: 0;
  animation: page-about-breathe 1.8s ease-in-out infinite;
}

@keyframes page-about-breathe {
  0%, 100% {
    transform: scale(1);
    opacity: 1;
  }
  50% {
    transform: scale(1.3);
    opacity: .6;
  }
}

.page-about__eng-note {
  margin-top: 1.4rem;
  font-size: .9rem;
  line-height: 1.65;
  color: rgba(245, 247, 250, .64);
  border-left: 3px solid var(--orange);
  padding-left: 1rem;
}

/* ===== 覆盖与边界 ===== */
.page-about__coverage-grid {
  display: grid;
  gap: 1.8rem;
  align-items: center;
}

.page-about__coverage-figure {
  margin: 0;
}

.page-about__coverage-figure img {
  width: 100%;
  height: auto;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  display: block;
}

.page-about__coverage-figure figcaption {
  margin-top: .65rem;
  font-size: .78rem;
  color: rgba(11, 30, 58, .62);
  font-family: var(--font-mono);
  letter-spacing: .03em;
  text-align: right;
}

.page-about__coverage-body {
  display: grid;
  gap: 1.2rem;
}

.page-about__coverage-block {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.3rem 1.4rem;
  box-shadow: 0 8px 20px rgba(3, 10, 22, .07);
}

.page-about__coverage-title {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 800;
  margin: 0 0 .55rem;
  display: flex;
  align-items: center;
  gap: .55rem;
}

.page-about__coverage-title::before {
  content: "";
  width: 12px;
  height: 12px;
  background: var(--orange);
  border-radius: 3px;
  display: inline-block;
  transform: rotate(45deg);
  flex-shrink: 0;
}

.page-about__coverage-block--boundary .page-about__coverage-title::before {
  background: var(--red);
}

.page-about__coverage-text {
  font-size: .95rem;
  line-height: 1.68;
  color: rgba(11, 30, 58, .78);
  margin: 0;
}

.page-about__coverage-list {
  list-style: none;
  margin: .85rem 0 0;
  padding: 0;
  display: grid;
  gap: .55rem;
}

.page-about__coverage-list li {
  position: relative;
  padding-left: 1.35rem;
  font-size: .93rem;
  line-height: 1.5;
  color: rgba(11, 30, 58, .82);
}

.page-about__coverage-list li::before {
  content: "▹";
  position: absolute;
  left: 0;
  color: var(--pulse);
  font-weight: 700;
}

/* ===== 团队与协同 ===== */
.page-about__team-wrap {
  display: grid;
  gap: 2rem;
}

.page-about__team-figure {
  margin: 0;
}

.page-about__team-figure img {
  width: 100%;
  height: auto;
  border-radius: var(--radius);
  border: 1px solid var(--line-dark);
  box-shadow: var(--shadow);
  display: block;
}

.page-about__team-figure figcaption {
  margin-top: .65rem;
  font-size: .78rem;
  color: rgba(245, 247, 250, .64);
  font-family: var(--font-mono);
  letter-spacing: .03em;
}

.page-about__team-content {
  display: grid;
  gap: 1.3rem;
}

.page-about__team-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: .9rem;
}

.page-about__team-card {
  position: relative;
  background: rgba(11, 30, 58, .35);
  border: 1px solid var(--line-dark);
  border-radius: var(--radius);
  padding: 1.1rem 1.2rem;
  overflow: hidden;
  transition: border-color .25s ease, transform .25s ease, background .25s ease;
}

.page-about__team-card::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--orange), var(--pulse));
  opacity: 0;
  transition: opacity .25s ease;
}

.page-about__team-card:hover {
  border-color: rgba(57, 255, 136, .5);
  transform: translateY(-3px);
  background: rgba(11, 30, 58, .52);
}

.page-about__team-card:hover::after {
  opacity: 1;
}

.page-about__team-card-num {
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .14em;
  color: var(--pulse);
  display: block;
  margin-bottom: .35rem;
  text-transform: uppercase;
}

.page-about__team-card-title {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 800;
  color: var(--paper);
  margin: 0 0 .35rem;
}

.page-about__team-card-desc {
  font-size: .87rem;
  line-height: 1.62;
  color: rgba(245, 247, 250, .68);
  margin: 0;
}

.page-about__team-note {
  margin: 0;
  font-size: .94rem;
  line-height: 1.72;
  color: rgba(245, 247, 250, .78);
  border-left: 3px solid var(--orange);
  padding-left: 1rem;
}

.page-about__team-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.page-about__team-cta .site-btn--primary {
  border: none;
}

/* ===== 桌面端增强 ===== */
@media (min-width: 640px) {
  .page-about__hero-stats {
    grid-template-columns: repeat(4, 1fr);
  }

  .page-about__eng-tag {
    display: inline-block;
  }

  .page-about__team-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (min-width: 860px) {
  .page-about__hero {
    padding: 4.2rem 0 5rem;
  }

  .page-about__hero-inner {
    grid-template-columns: 7fr 5fr;
    gap: 3.5rem;
  }

  .page-about__hero-lead {
    font-size: 1.08rem;
  }

  .page-about__timeline::before {
    left: 50%;
    transform: translateX(-50%);
    width: 3px;
  }

  .page-about__timeline-item {
    width: 50%;
    padding: 0 3rem 0 0;
  }

  .page-about__timeline-item.is-left {
    left: 0;
  }

  .page-about__timeline-item.is-right {
    left: 50%;
    padding: 0 0 0 3rem;
  }

  .page-about__timeline-dot {
    left: auto;
    right: -10px;
    width: 18px;
    height: 18px;
    top: 1.6rem;
  }

  .page-about__timeline-item.is-right .page-about__timeline-dot {
    left: -10px;
    right: auto;
  }

  .page-about__timeline-item.is-left .page-about__timeline-card {
    margin-left: auto;
  }

  .page-about__eng-stack {
    margin-top: .5rem;
  }

  .page-about__eng-layer--two {
    transform: translateX(5%);
  }

  .page-about__eng-layer--three {
    transform: translateX(10%);
  }

  .page-about__coverage-grid {
    grid-template-columns: 1.18fr 1fr;
    gap: 3rem;
  }

  .page-about__team-wrap {
    grid-template-columns: 5fr 7fr;
    gap: 3rem;
    align-items: center;
  }
}

@media (min-width: 1100px) {
  .page-about__team-card {
    padding: 1.25rem 1.35rem;
  }
}