.page-about {
  --about-num: clamp(30px, 6vw, 52px);
  --about-num-col: 44px;
  background: var(--ink);
  color: var(--bone);
  padding-bottom: clamp(48px, 8vw, 96px);
  overflow-x: clip;
}

.page-about .breadcrumb {
  padding-top: clamp(16px, 2.4vw, 28px);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--steel);
}

.page-about .breadcrumb__link {
  color: var(--steel);
  text-decoration: none;
}

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

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

.page-about .breadcrumb__now {
  color: var(--bone);
}

.page-about img {
  display: block;
  max-width: 100%;
  height: auto;
}

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

.page-about .media__caption {
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--steel);
  line-height: 1.6;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-top: clamp(22px, 3.6vw, 44px);
  padding-bottom: clamp(30px, 4.6vw, 56px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__kicker {
  margin: 0 0 clamp(16px, 2.4vw, 26px);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--amber);
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(18px, 3vw, 40px);
}

.page-about .about-hero__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(32px, 7.2vw, 86px);
  line-height: 1.02;
  letter-spacing: -0.02em;
  color: var(--bone);
  text-shadow: 0 0 20px rgba(47, 227, 208, 0.2);
}

.page-about .about-hero__lead {
  margin: 0;
  max-width: 38ch;
  font-size: 16px;
  line-height: 1.78;
  color: rgba(242, 241, 232, 0.84);
}

.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  list-style: none;
  margin: clamp(26px, 4vw, 46px) 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .about-hero__facts li {
  flex: 1 1 160px;
  padding: 16px 20px 16px 0;
  border-right: 1px solid var(--line);
}

.page-about .about-hero__facts li:last-child {
  border-right: 0;
  padding-right: 0;
}

.page-about .about-hero__facts li > .num {
  display: block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: clamp(28px, 4.4vw, 46px);
  line-height: 1;
  color: var(--cyan);
  letter-spacing: -0.02em;
}

.page-about .about-hero__facts li > span:not(.num) {
  display: block;
  font-size: 13px;
  line-height: 1.6;
  color: var(--steel);
  max-width: 22ch;
}

.page-about .about-hero .note-vertical {
  display: none;
  color: var(--clay);
}

/* ---------- 章节目录 ---------- */
.page-about .about-toc {
  position: sticky;
  top: 0;
  z-index: 12;
  background: rgba(7, 19, 15, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}

.page-about .about-toc__inner {
  display: flex;
  flex-wrap: nowrap;
  gap: 0;
  overflow-x: auto;
  scrollbar-width: thin;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-toc__inner::-webkit-scrollbar {
  height: 3px;
}

.page-about .about-toc__inner::-webkit-scrollbar-thumb {
  background: var(--line);
}

.page-about .about-toc .toc-link {
  flex: 0 0 auto;
  display: inline-block;
  padding: 14px 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  white-space: nowrap;
  text-decoration: none;
  color: var(--steel);
  border-bottom: 2px solid transparent;
  transition: color 160ms ease, border-color 160ms ease;
}

.page-about .about-toc .toc-link:hover,
.page-about .about-toc .toc-link:focus-visible {
  color: var(--bone);
}

.page-about .about-toc .toc-link[aria-current="true"] {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* ---------- 章节通用 ---------- */
.page-about .about-sec {
  padding-top: clamp(40px, 6.4vw, 84px);
  padding-bottom: clamp(30px, 4.6vw, 56px);
  border-bottom: 1px solid var(--line);
}

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

.page-about .section-head {
  margin-bottom: clamp(22px, 3.6vw, 44px);
}

/* ---------- 01 起点 ---------- */
.page-about .about-origin {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(20px, 3.2vw, 44px);
  align-items: start;
}

.page-about .about-origin__text p {
  margin: 0 0 16px;
  max-width: 38ch;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(242, 241, 232, 0.84);
}

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

.page-about .about-origin__media {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--panel);
}

.page-about .about-origin__media .media__caption {
  padding: 10px 12px;
  border-top: 1px solid var(--line);
}

/* ---------- 02 时间轴 ---------- */
.page-about .about-tl {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.page-about .about-tl::before {
  content: "";
  position: absolute;
  left: calc(var(--about-num-col) / 2);
  top: 6px;
  bottom: 24px;
  width: 1px;
  background: var(--line);
}

.page-about .about-node {
  position: relative;
  padding: 0 0 clamp(30px, 5vw, 54px) calc(var(--about-num-col) + 18px);
}

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

.page-about .about-node__num {
  position: absolute;
  left: 0;
  top: -6px;
  width: var(--about-num-col);
  padding-bottom: 8px;
  background: var(--ink);
  font-family: var(--font-mono);
  font-size: var(--about-num);
  line-height: 1;
  letter-spacing: -0.05em;
  text-align: center;
  color: var(--amber);
  transition: color 200ms ease;
}

.page-about .about-node:hover .about-node__num {
  color: var(--magenta);
}

.page-about .about-node__year {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.24em;
  color: var(--cyan);
}

.page-about .about-node__title {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-size: clamp(19px, 2.8vw, 28px);
  font-weight: 700;
  line-height: 1.24;
  letter-spacing: -0.01em;
  color: var(--bone);
}

.page-about .about-node__text {
  margin: 0 0 14px;
  max-width: 38ch;
  font-size: 15.5px;
  line-height: 1.8;
  color: rgba(242, 241, 232, 0.82);
}

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

.page-about .about-node__quote {
  margin: 0 0 14px;
  padding-left: 14px;
  border-left: 2px solid var(--amber);
  font-family: var(--font-display);
  font-weight: 400;
  font-size: clamp(18px, 2.5vw, 26px);
  line-height: 1.36;
  letter-spacing: -0.01em;
  color: var(--bone);
}

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

.page-about .about-node__list li {
  padding: 6px 10px;
  border: 1px solid var(--line);
  background: var(--panel);
  font-size: 12.5px;
  letter-spacing: 0.02em;
  color: var(--steel);
}

/* ---------- 03 团队 ---------- */
.page-about .about-team__media {
  margin: 0 0 clamp(20px, 3vw, 32px);
  border: 1px solid var(--line);
}

.page-about .about-team__media .media__caption {
  padding: 10px 12px;
  border-top: 1px solid var(--line);
}

.page-about .about-team__lead {
  margin: 0 0 clamp(18px, 2.6vw, 28px);
  max-width: 40ch;
  font-size: 16px;
  line-height: 1.78;
  color: rgba(242, 241, 232, 0.84);
}

.page-about .about-team {
  border-top: 1px solid var(--line);
}

.page-about .about-bar {
  border-bottom: 1px solid var(--line);
  transition: background 220ms ease;
}

.page-about .about-bar[open] {
  background: var(--panel);
}

.page-about .about-bar__summary {
  position: relative;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: baseline;
  gap: 14px;
  padding: 18px 12px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-bar__summary::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: 2px;
  width: var(--w, 30%);
  background: linear-gradient(90deg, var(--cyan), rgba(47, 227, 208, 0.12));
  transition: background 220ms ease;
}

.page-about .about-bar[open] .about-bar__summary::after {
  background: linear-gradient(90deg, var(--amber), rgba(240, 176, 60, 0.12));
}

.page-about .about-bar__summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: -2px;
}

.page-about .about-bar__label {
  font-family: var(--font-display);
  font-size: clamp(16px, 2.2vw, 22px);
  letter-spacing: -0.01em;
  color: var(--bone);
}

.page-about .about-bar__num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 3.8vw, 40px);
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-bar[open] .about-bar__num {
  color: var(--amber);
}

.page-about .about-bar__detail {
  padding: 0 12px 20px;
  max-width: 54ch;
  font-size: 14.5px;
  line-height: 1.78;
  color: rgba(242, 241, 232, 0.8);
}

.page-about .about-bar__detail p {
  margin: 0 0 10px;
}

.page-about .about-bar__detail ul {
  margin: 0;
  padding-left: 18px;
  color: var(--steel);
  font-size: 13.5px;
  line-height: 1.9;
}

.page-about .about-bar__detail li::marker {
  color: var(--cyan);
}

.page-about .about-team__foot {
  margin: clamp(18px, 2.6vw, 28px) 0 0;
  max-width: 44ch;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--steel);
}

.page-about .about-team__foot a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(47, 227, 208, 0.4);
}

.page-about .about-team__foot a:hover {
  border-bottom-color: var(--cyan);
}

/* ---------- 04 服务区域 ---------- */
.page-about .about-region {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(22px, 3.4vw, 44px);
  align-items: center;
}

.page-about .about-region__copy p {
  margin: 0 0 16px;
  max-width: 40ch;
  font-size: 15.5px;
  line-height: 1.8;
  color: rgba(242, 241, 232, 0.84);
}

.page-about .about-region__stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 1px;
  margin-top: clamp(18px, 2.6vw, 26px);
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-region__stats > div {
  background: var(--ink);
  padding: 16px 14px;
}

.page-about .about-region__stats .num {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.4vw, 34px);
  line-height: 1;
  color: var(--cyan);
}

.page-about .about-region__stats span:last-child {
  display: block;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--steel);
}

.page-about .about-region__media {
  margin: 0;
  border: 1px solid var(--line);
  background: var(--panel);
}

.page-about .about-region__media .media__caption {
  padding: 10px 12px;
  border-top: 1px solid var(--line);
}

/* ---------- 05 教程产出 ---------- */
.page-about .about-tut {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(22px, 3.4vw, 48px);
  align-items: start;
}

.page-about .about-tut__copy p {
  margin: 0 0 16px;
  max-width: 38ch;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(242, 241, 232, 0.84);
}

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

.page-about .about-tut__copy a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(47, 227, 208, 0.4);
}

.page-about .about-rhythm {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-rhythm li {
  display: grid;
  grid-template-columns: minmax(64px, 88px) 1fr;
  gap: 16px;
  align-items: baseline;
  padding: 16px 0;
  border-top: 1px solid var(--line);
}

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

.page-about .about-rhythm .num {
  font-family: var(--font-mono);
  font-size: clamp(20px, 2.8vw, 28px);
  line-height: 1;
  color: var(--amber);
  letter-spacing: -0.02em;
}

.page-about .about-rhythm li > span:last-child {
  font-size: 14px;
  line-height: 1.75;
  color: rgba(242, 241, 232, 0.78);
}

/* ---------- 06 接下来 ---------- */
.page-about .about-next {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(20px, 2.8vw, 32px);
}

.page-about .about-next li {
  padding-left: 16px;
  border-left: 2px solid var(--line);
  transition: border-color 220ms ease;
}

.page-about .about-next li:hover {
  border-left-color: var(--cyan);
}

.page-about .about-next h3 {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: clamp(17px, 2.2vw, 21px);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--bone);
}

.page-about .about-next p {
  margin: 0;
  max-width: 36ch;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(242, 241, 232, 0.76);
}

.page-about .about-cta {
  margin-top: clamp(28px, 4.4vw, 52px);
  padding-top: clamp(22px, 3vw, 34px);
  border-top: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.page-about .about-cta__text {
  margin: 0;
  max-width: 40ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--bone);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about .about-next {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-cta {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

@media (min-width: 880px) {
  .page-about {
    --about-num: clamp(46px, 4.6vw, 64px);
    --about-num-col: 60px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
    align-items: end;
  }

  .page-about .about-hero__side {
    padding-bottom: 8px;
  }

  .page-about .about-hero .note-vertical {
    display: block;
    position: absolute;
    right: 0;
    top: clamp(80px, 10vw, 130px);
    writing-mode: vertical-rl;
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: 0.32em;
    color: var(--clay);
  }

  .page-about .about-origin {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  }

  .page-about .about-tut {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: clamp(32px, 4vw, 64px);
  }

  .page-about .about-region {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr);
  }

  .page-about .about-node {
    padding-left: calc(var(--about-num-col) + 28px);
  }
}

@media (min-width: 1180px) {
  .page-about .about-tut {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
  }

  .page-about .about-node__text,
  .page-about .about-origin__text p {
    font-size: 16.5px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-node__num,
  .page-about .about-bar,
  .page-about .about-node__num,
  .page-about .about-next li {
    transition: none;
  }
}

.page-about {
  --w: 1rem;
}