.page-about {
  --about-shadow: 8px 8px 0 rgba(4, 14, 28, .92);
  --about-shadow-ice: 8px 8px 0 rgba(12, 37, 66, .2);
  --about-gap: clamp(64px, 9vw, 112px);
}

/* ---------- 面包屑 ---------- */
.page-about .page-about__crumbs {
  padding-top: clamp(20px, 3vw, 34px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(20px, 3.5vw, 42px) 0 clamp(56px, 8vw, 104px);
}

.page-about .about-hero__inner {
  display: grid;
  gap: 40px;
}

@media (min-width: 1000px) {
  .page-about .about-hero__inner {
    grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
    gap: clamp(40px, 5vw, 76px);
    align-items: start;
  }
}

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

.page-about .about-hero__title {
  margin: 14px 0 0;
  max-width: 20ch;
  color: var(--ice);
}

.page-about .about-hero__lede {
  margin-top: 22px;
  max-width: 44ch;
  color: var(--ice);
  opacity: .84;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 30px;
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 3px solid var(--line-strong);
  box-shadow: var(--about-shadow);
}

.page-about .about-hero__stat {
  background: var(--deep);
  padding: 22px 18px;
  min-width: 0;
}

.page-about .about-hero__num {
  margin: 0;
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: clamp(22px, 2.6vw, 32px);
  line-height: 1.05;
  letter-spacing: .02em;
  color: var(--amber);
}

.page-about .about-hero__label {
  margin: 10px 0 0;
  font-size: 13px;
  line-height: 1.6;
  color: var(--steel);
}

/* ---------- 章节头 ---------- */
.page-about .about-sec-head {
  margin-bottom: clamp(36px, 5vw, 56px);
}

.page-about .about-sec-head__note {
  margin-top: 16px;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--steel);
}

.page-about .zone--ice .about-sec-head__note {
  color: var(--slate);
}

/* ---------- 时间轴 ---------- */
.page-about .about-timeline__figure {
  margin: 0 0 clamp(44px, 6vw, 72px);
}

.page-about .about-timeline__grid {
  display: grid;
  gap: 30px;
}

@media (min-width: 900px) {
  .page-about .about-timeline__grid {
    grid-template-columns: 172px minmax(0, 1fr);
    gap: clamp(44px, 5.5vw, 84px);
  }
}

.page-about .about-rail {
  min-width: 0;
}

@media (min-width: 900px) {
  .page-about .about-rail {
    position: sticky;
    top: 132px;
    align-self: start;
  }
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 6px 0 0 26px;
  border-left: 2px solid var(--line);
}

@media (max-width: 899px) {
  .page-about .about-rail__list {
    display: flex;
    gap: 22px;
    overflow-x: auto;
    padding: 18px 0 0;
    border-left: 0;
    border-top: 2px solid var(--line);
    -webkit-overflow-scrolling: touch;
  }
}

.page-about .about-rail__name {
  display: block;
  margin-top: 6px;
  font-family: var(--font-narrow);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .14em;
  color: var(--steel);
}

@media (max-width: 899px) {
  .page-about .about-rail__name {
    display: none;
  }
}

.page-about .rail__item {
  position: relative;
  padding-bottom: 30px;
}

@media (max-width: 899px) {
  .page-about .rail__item {
    flex: 0 0 auto;
    padding-bottom: 22px;
  }
}

.page-about .rail__item::before {
  content: "";
  position: absolute;
  left: -33px;
  top: 12px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--midnight);
  border: 2px solid var(--steel);
  transition: background var(--t) var(--ease), border-color var(--t) var(--ease), box-shadow var(--t) var(--ease);
}

@media (max-width: 899px) {
  .page-about .rail__item::before {
    display: none;
  }
}

.page-about .rail__item.is-active::before {
  background: var(--cyan);
  border-color: var(--cyan);
  box-shadow: 0 0 0 5px rgba(79, 227, 208, .16), 0 0 16px rgba(79, 227, 208, .5);
}

.page-about .rail__link {
  display: block;
  text-decoration: none;
  color: var(--steel);
  transition: color var(--t) var(--ease);
}

.page-about .rail__link:hover {
  color: var(--ice);
}

.page-about .rail__time {
  display: block;
  font-family: var(--font-narrow);
  font-weight: 600;
  font-size: clamp(22px, 2.6vw, 36px);
  line-height: 1.02;
  letter-spacing: -0.01em;
  color: var(--steel);
  transition: color var(--t) var(--ease);
}

.page-about .rail__item.is-active .rail__time {
  color: var(--cyan);
}

.page-about .rail__item.is-active .about-rail__name {
  color: var(--ice);
}

.page-about .about-node {
  padding-bottom: clamp(52px, 7.5vw, 96px);
}

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

.page-about .about-node__title {
  margin: 0 0 14px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(19px, 2.1vw, 25px);
  line-height: 1.42;
  color: var(--ice);
}

.page-about .about-node p {
  margin: 0;
  max-width: 58ch;
  font-size: 16px;
  line-height: 1.82;
  color: var(--steel);
}

/* ---------- 团队 ---------- */
.page-about .about-team__intro {
  display: grid;
  gap: 32px;
  margin-bottom: clamp(44px, 6vw, 68px);
}

@media (min-width: 900px) {
  .page-about .about-team__intro {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: clamp(36px, 5vw, 72px);
    align-items: center;
  }
}

.page-about .about-team__text p {
  margin: 0 0 18px;
  max-width: 46ch;
  font-size: 16px;
  line-height: 1.82;
  color: var(--slate);
}

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

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

.page-about .about-teambar {
  display: flex;
  height: 60px;
  border: 3px solid var(--midnight);
  box-shadow: var(--about-shadow-ice);
  background: var(--frost);
}

@media (max-width: 719px) {
  .page-about .about-teambar {
    flex-direction: column;
    height: auto;
  }
}

.page-about .about-teambar__seg {
  position: relative;
  display: block;
  min-width: 0;
  flex: 0 0 var(--seg, auto);
  cursor: default;
  transition: filter var(--t) var(--ease);
}

.page-about .about-teambar__seg:hover,
.page-about .about-teambar__seg:focus {
  filter: brightness(1.08);
}

.page-about .about-teambar__seg--dev {
  --seg: 61.4%;
  background: var(--cyan);
}

.page-about .about-teambar__seg--data {
  --seg: 17.2%;
  background: var(--violet);
}

.page-about .about-teambar__seg--cs {
  --seg: 21.4%;
  background: var(--steel);
}

@media (max-width: 719px) {
  .page-about .about-teambar__seg {
    flex: 0 0 auto;
    width: 100%;
    height: 46px;
  }
}

.page-about .about-teambar__tip {
  position: absolute;
  bottom: calc(100% + 12px);
  left: 50%;
  transform: translate(-50%, 6px);
  padding: 7px 11px;
  background: var(--midnight);
  border: 1px solid var(--line-strong);
  color: var(--ice);
  font-family: var(--font-body);
  font-size: 12px;
  line-height: 1.4;
  letter-spacing: .02em;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  z-index: 4;
  transition: opacity var(--t) var(--ease), transform var(--t) var(--ease);
}

@media (max-width: 719px) {
  .page-about .about-teambar__tip {
    display: none;
  }
}

.page-about .about-teambar__seg:hover .about-teambar__tip,
.page-about .about-teambar__seg:focus .about-teambar__tip {
  opacity: 1;
  transform: translate(-50%, 0);
}

.page-about .about-team__legend {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 26px;
  margin-top: 20px;
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--slate);
}

.page-about .about-team__legend-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.page-about .about-dot {
  width: 10px;
  height: 10px;
  display: inline-block;
}

.page-about .about-dot--cyan { background: var(--cyan); }
.page-about .about-dot--violet { background: var(--violet); }
.page-about .about-dot--steel { background: var(--steel); }

.page-about .about-team__roles {
  margin-top: clamp(44px, 6vw, 68px);
  gap: 22px;
}

.page-about .about-role {
  border-top: 2px solid var(--midnight);
  padding-top: 18px;
}

.page-about .about-role__tag {
  color: var(--slate);
}

.page-about .about-role__title {
  margin: 12px 0 12px;
  font-family: var(--font-narrow);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: .01em;
  color: var(--midnight);
}

.page-about .about-role p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--slate);
}

/* ---------- 基础设施 ---------- */
.page-about .about-infra__figure {
  margin: 0 0 clamp(40px, 5.5vw, 64px);
}

.page-about .about-region {
  border-left: 3px solid var(--cyan-deep);
  padding: 4px 0 4px 20px;
}

.page-about .about-region__code {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--cyan);
}

.page-about .about-region__name {
  margin: 10px 0 10px;
  font-family: var(--font-narrow);
  font-weight: 600;
  font-size: 20px;
  color: var(--ice);
}

.page-about .about-region p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--steel);
}

.page-about .about-infra__note {
  position: relative;
  margin-top: clamp(40px, 5.5vw, 64px);
}

.page-about .about-infra__note p {
  margin: 0;
  max-width: 70ch;
  font-size: 16px;
  line-height: 1.82;
  color: var(--steel);
}

/* ---------- 安全 ---------- */
.page-about .about-security__grid {
  display: grid;
  gap: 40px;
}

@media (min-width: 900px) {
  .page-about .about-security__grid {
    grid-template-columns: 260px minmax(0, 1fr);
    gap: clamp(44px, 6vw, 88px);
    align-items: center;
  }
}

.page-about .about-rings {
  position: relative;
  width: 220px;
  height: 220px;
  margin: 0 auto;
}

.page-about .about-rings__ring {
  position: absolute;
  border-radius: 50%;
  border: 1px solid var(--line);
}

.page-about .about-rings__ring--1 { inset: 0; }

.page-about .about-rings__ring--2 {
  inset: 26px;
  border-style: dashed;
  border-color: var(--line-strong);
}

.page-about .about-rings__ring--3 {
  inset: 54px;
  border-color: rgba(79, 227, 208, .48);
}

.page-about .about-rings__core {
  position: absolute;
  inset: 80px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  border: 2px solid var(--cyan);
  background: radial-gradient(circle at 34% 28%, rgba(79, 227, 208, .42), rgba(31, 156, 156, .1) 72%);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--cyan);
}

.page-about .about-security__points {
  display: grid;
  gap: 26px;
}

@media (min-width: 700px) {
  .page-about .about-security__points {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 26px clamp(26px, 3.5vw, 48px);
  }
}

.page-about .about-point {
  border-top: 1px solid var(--line-strong);
  padding-top: 16px;
}

.page-about .about-point__title {
  margin: 0 0 10px;
  font-family: var(--font-narrow);
  font-weight: 600;
  font-size: 17px;
  letter-spacing: .01em;
  color: var(--cyan);
}

.page-about .about-point p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--steel);
}

/* ---------- 服务 ---------- */
.page-about .about-service__grid {
  gap: 30px clamp(28px, 4vw, 56px);
}

.page-about .about-service__item {
  border-left: 3px solid var(--violet);
  padding: 2px 0 2px 20px;
}

.page-about .about-service__tag {
  color: var(--slate);
}

.page-about .about-service__item h3 {
  margin: 12px 0 12px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(18px, 1.9vw, 22px);
  line-height: 1.45;
  color: var(--midnight);
}

.page-about .about-service__item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--slate);
}

.page-about .about-service__item a {
  color: var(--cyan-deep);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-service__block {
  margin-top: clamp(44px, 6vw, 68px);
  border-top: 3px solid var(--midnight);
  padding-top: 26px;
}

.page-about .about-service__blocktitle {
  margin: 0 0 20px;
  font-family: var(--font-narrow);
  font-weight: 600;
  font-size: 20px;
  letter-spacing: .01em;
  color: var(--midnight);
}

.page-about .about-service__links {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}