.page-about {
  --about-line: #E3E9F0;
  --about-soft: #F5F8FB;
  --about-cut: 18px;
  background: var(--snow);
  color: var(--night);
  font-family: var(--font-body);
  overflow-wrap: break-word;
}

.page-about__inner {
  width: 100%;
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 2rem clamp(1rem, 4vw, 3rem) 4rem;
}

.page-about .breadcrumb {
  margin-bottom: clamp(2rem, 5vw, 3.5rem);
}

.about-hero {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  margin-bottom: clamp(2rem, 6vw, 3.5rem);
}

.about-hero .about-kicker {
  display: flex;
  align-items: center;
  gap: .65rem;
  margin: 0 0 1rem;
  font-size: .8125rem;
  font-weight: 700;
  letter-spacing: .18em;
  color: var(--plateau);
  text-transform: uppercase;
}

.about-kicker::before {
  content: "";
  width: 32px;
  height: 3px;
  background: var(--plateau);
  display: inline-block;
}

.about-hero .page-title {
  margin: 0 0 1.25rem;
  font-family: var(--font-display);
  font-size: clamp(2rem, 6vw, 3.4rem);
  line-height: 1.18;
  letter-spacing: .01em;
  color: var(--night);
  font-weight: 700;
}

.about-hero .lead {
  margin: 0 0 1.5rem;
  font-size: clamp(.9375rem, 1.4vw, 1.0625rem);
  line-height: 1.85;
  color: var(--ink-gray);
  max-width: 46em;
}

.about-hero__tags {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
}

.about-hero__aside {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(7.5rem, 1fr));
  gap: .875rem;
  background: var(--night);
  color: var(--snow);
  padding: 1.5rem 1.25rem 1.25rem;
  position: relative;
  overflow: hidden;
}

.about-hero__aside::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--plateau) 0%, var(--flag-yellow) 55%, var(--flag-red) 100%);
}

.about-stat {
  display: flex;
  flex-direction: column;
  gap: .35rem;
}

.about-stat__num {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.05;
  color: #ffffff;
}

.about-stat__label {
  font-size: .8125rem;
  color: rgba(248, 250, 252, .78);
  letter-spacing: .04em;
}

/* 章节预览 */
.about-chapters {
  margin-bottom: clamp(3rem, 8vw, 5.5rem);
}

.about-chapters__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.about-chapters__title {
  font-family: var(--font-display);
  font-size: 1.5rem;
  margin: 0;
}

.about-chapters .vertical-note {
  writing-mode: vertical-rl;
  font-size: .75rem;
  letter-spacing: .2em;
  color: var(--ink-gray);
  border-left: 2px solid var(--peak-blue);
  padding-left: .5rem;
  height: 4.5rem;
}

.chapter-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: .875rem;
}

.chapter-card {
  display: grid;
  grid-template-columns: auto 1fr;
  grid-template-rows: auto auto;
  column-gap: 1rem;
  row-gap: .25rem;
  text-decoration: none;
  color: var(--night);
  background: var(--about-soft);
  border: 1px solid var(--about-line);
  border-left: 4px solid var(--plateau);
  padding: 1.25rem 1.5rem;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
}

.chapter-card:hover {
  background: #ffffff;
  transform: translateX(4px);
  box-shadow: var(--shadow-soft);
}

.chapter-card__num {
  grid-row: 1 / 3;
  font-family: var(--font-display);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--plateau);
  line-height: 1.2;
  padding-right: .25rem;
  position: relative;
}

.chapter-card__num::after {
  content: "";
  position: absolute;
  right: 0;
  top: .25rem;
  bottom: .25rem;
  width: 1px;
  background: var(--peak-blue);
}

.chapter-card__name {
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 700;
}

.chapter-card__desc {
  font-size: .875rem;
  color: var(--ink-gray);
}

/* 时间轴 */
.milestone-section {
  margin-bottom: clamp(3.5rem, 10vw, 7rem);
}

@media (min-width: 960px) {
  .milestone-section {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 260px;
    gap: 2.5rem;
    align-items: start;
  }
}

.milestone-lead {
  color: var(--ink-gray);
  font-size: .9375rem;
  line-height: 1.8;
  max-width: 38em;
}

.timeline {
  margin-top: 2rem;
}

.timeline-item {
  position: relative;
  padding: 0 0 2.25rem 3.5rem;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: 11px;
  top: 12px;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--peak-blue), var(--about-line) 68%, transparent);
}

.timeline-item:last-child::before {
  display: none;
}

.timeline-dot {
  position: absolute;
  left: 0;
  top: .45rem;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  z-index: 1;
  box-shadow: 0 0 0 5px rgba(10, 77, 162, .1);
}

.timeline-dot--red { background: var(--flag-red); box-shadow: 0 0 0 5px rgba(200, 16, 46, .12); }
.timeline-dot--yellow { background: var(--flag-yellow); box-shadow: 0 0 0 5px rgba(242, 169, 0, .14); }
.timeline-dot--green { background: var(--flag-green); box-shadow: 0 0 0 5px rgba(0, 140, 90, .12); }
.timeline-dot--blue { background: var(--plateau); box-shadow: 0 0 0 5px rgba(10, 77, 162, .12); }

.timeline-card {
  position: relative;
  background: #ffffff;
  padding: 1.5rem;
  border: 1px solid var(--about-line);
  border-top: 3px solid var(--about-line);
  transition: box-shadow var(--transition), border-color var(--transition);
}

.timeline-card:hover {
  box-shadow: var(--shadow-soft);
}

.timeline-item--current .timeline-card {
  border-top: 3px solid var(--plateau);
}

.timeline-card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: .75rem;
  margin-bottom: .75rem;
}

.timeline-card__year {
  font-family: var(--font-display);
  font-size: 1.75rem;
  margin: 0;
  color: var(--night);
  line-height: 1.1;
}

.timeline-card p {
  margin: .35rem 0;
  color: var(--ink-gray);
  font-size: .9375rem;
  line-height: 1.75;
}

.timeline-detail {
  margin-top: .75rem;
  border-top: 1px dashed var(--about-line);
  padding-top: .5rem;
}

.timeline-detail summary {
  list-style: none;
  cursor: pointer;
  font-size: .8125rem;
  font-weight: 700;
  letter-spacing: .08em;
  color: var(--plateau);
  padding: .5rem 0 .25rem;
  display: inline-flex;
  align-items: center;
  gap: .4rem;
}

.timeline-detail summary::-webkit-details-marker {
  display: none;
}

.timeline-detail summary::before {
  content: "＋";
  display: inline-block;
  font-size: .875rem;
  color: var(--flag-red);
}

.timeline-detail[open] summary::before {
  content: "－";
}

.timeline-detail p {
  font-size: .875rem;
  color: var(--ink-gray);
  line-height: 1.8;
  padding-top: .5rem;
}

/* 右侧图表 */
.about-viz {
  margin: 2rem auto 0;
  max-width: 320px;
  position: relative;
}

@media (min-width: 960px) {
  .about-viz {
    margin: 3.5rem 0 0 auto;
    max-width: 260px;
  }
}

.about-viz img {
  display: block;
  width: 100%;
  height: auto;
  clip-path: polygon(0 0, calc(100% - 20px) 0, 100% 20px, 100% 100%, 20px 100%, 0 calc(100% - 20px));
}

.about-viz figcaption,
.about-landscape figcaption,
.about-band figcaption {
  font-size: .75rem;
  color: var(--ink-gray);
  margin-top: .5rem;
  letter-spacing: .06em;
  text-align: right;
}

.about-landscape {
  margin: 0 0 clamp(3rem, 8vw, 5.5rem);
}

.about-landscape img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 24px), calc(100% - 24px) 100%, 0 100%);
}

.about-landscape figcaption {
  text-align: left;
}

/* 服务理念 */
.philosophy-section {
  margin-bottom: clamp(3.5rem, 10vw, 6.5rem);
}

.philosophy-lead,
.team-lead,
.data-flow-lead {
  color: var(--ink-gray);
  font-size: .9375rem;
  line-height: 1.8;
  max-width: 40em;
}

.philosophy-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin: 2rem 0;
}

@media (min-width: 900px) {
  .philosophy-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
  }

  .philosophy-card:nth-child(2) {
    transform: translateY(14px);
  }
}

.philosophy-card {
  position: relative;
  background: #ffffff;
  padding: 1.5rem;
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition);
}

.philosophy-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-soft);
}

.philosophy-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--plateau), var(--peak-blue));
}

.philosophy-card:nth-child(2)::before {
  background: linear-gradient(90deg, var(--flag-yellow), var(--flag-red));
}

.philosophy-card:nth-child(3)::before {
  background: linear-gradient(90deg, var(--flag-green), var(--plateau));
}

.philosophy-card__num {
  display: block;
  font-family: var(--font-display);
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--plateau);
  opacity: .3;
  line-height: 1;
  margin-bottom: .75rem;
}

.philosophy-card__title {
  font-family: var(--font-display);
  font-size: 1.25rem;
  margin: 0 0 .75rem;
}

.philosophy-card p {
  margin: 0 0 .75rem;
  font-size: .875rem;
  line-height: 1.75;
  color: var(--ink-gray);
}

.philosophy-card__en {
  margin-top: auto;
  font-size: .8125rem;
  letter-spacing: .02em;
  color: var(--ink-gray);
  border-left: 2px solid var(--peak-blue);
  padding-left: .75rem;
  font-style: italic;
}

.philosophy-explain {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  background: var(--about-soft);
  border: 1px solid var(--about-line);
  border-right: 4px solid var(--plateau);
  padding: 1.5rem;
}

@media (min-width: 760px) {
  .philosophy-explain {
    grid-template-columns: 240px 1fr;
    align-items: start;
  }
}

.philosophy-explain h3 {
  font-family: var(--font-display);
  font-size: 1.0625rem;
  margin: 0;
}

.philosophy-explain p {
  margin: 0;
  color: var(--ink-gray);
  line-height: 1.8;
  font-size: .9375rem;
}

/* 团队 */
.team-section {
  margin-bottom: clamp(3.5rem, 10vw, 6.5rem);
}

.team-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 2rem;
}

@media (min-width: 900px) {
  .team-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
  }
}

.team-card {
  background: #ffffff;
  padding: 1.75rem 1.5rem;
  border: 1px solid var(--about-line);
  border-top: 5px solid var(--plateau);
  transition: box-shadow var(--transition), border-color var(--transition);
}

.team-card:hover {
  border-color: var(--peak-blue);
  box-shadow: var(--shadow-soft);
}

.team-card:nth-child(2) {
  border-top-color: var(--flag-yellow);
}

.team-card:nth-child(3) {
  border-top-color: var(--flag-green);
}

.team-card__title {
  font-family: var(--font-display);
  font-size: 1.375rem;
  margin: 0 0 .25rem;
}

.team-card__sub {
  font-size: .75rem;
  letter-spacing: .14em;
  color: var(--plateau);
  margin: 0 0 1rem;
  font-weight: 600;
}

.team-card p {
  font-size: .875rem;
  line-height: 1.75;
  color: var(--ink-gray);
  margin: 0 0 .875rem;
}

.team-card__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.team-card__list li {
  position: relative;
  padding: .35rem 0 .35rem 1.25rem;
  font-size: .8125rem;
  color: var(--night);
  line-height: 1.6;
  border-bottom: 1px dotted var(--about-line);
}

.team-card__list li:last-child {
  border-bottom: 0;
}

.team-card__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .85rem;
  width: 7px;
  height: 7px;
  background: var(--flag-yellow);
  transform: rotate(45deg);
}

/* 数据流程 */
.data-flow-section {
  margin-bottom: clamp(3rem, 8vw, 5rem);
}

.flow-steps {
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  counter-reset: flow-counter;
}

@media (min-width: 900px) {
  .flow-steps {
    grid-template-columns: repeat(4, 1fr);
    gap: 1.25rem;
  }
}

.flow-step {
  position: relative;
  background: var(--about-soft);
  border: 1px solid var(--about-line);
  border-bottom: 3px solid var(--peak-blue);
  padding: 1.25rem 1.25rem 1.5rem;
  transition: background var(--transition), border-color var(--transition), transform var(--transition), box-shadow var(--transition);
}

.flow-step:hover {
  background: #ffffff;
  border-color: var(--plateau);
  border-bottom-color: var(--flag-red);
  transform: translateY(-3px);
  box-shadow: var(--shadow-soft);
}

.flow-step:nth-child(2) { border-bottom-color: var(--flag-yellow); }
.flow-step:nth-child(3) { border-bottom-color: var(--flag-green); }
.flow-step:nth-child(4) { border-bottom-color: var(--flag-red); }

.flow-step__num {
  display: block;
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--plateau);
  margin-bottom: .5rem;
}

.flow-step h3 {
  font-family: var(--font-display);
  font-size: 1.0625rem;
  margin: 0 0 .5rem;
}

.flow-step p {
  margin: 0;
  font-size: .8125rem;
  line-height: 1.7;
  color: var(--ink-gray);
}

@media (min-width: 900px) {
  .flow-step::after {
    content: "→";
    position: absolute;
    right: -1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--peak-blue);
    font-size: 1.25rem;
    font-weight: 700;
    z-index: 2;
    background: var(--snow);
    padding: 0 .25rem;
  }

  .flow-step:last-child::after {
    display: none;
  }
}

/* 品牌色带 */
.about-band {
  margin: 0 0 3rem;
}

.about-band img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

/* 相关入口 */
.about-related {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  padding-top: 2rem;
  border-top: 1px solid var(--about-line);
}