.page-about {
  background: var(--paper);
  color: var(--ink);
}

/* 面包屑条 */
.page-about .about-crumb-bar {
  padding-block: .9rem;
  border-bottom: 1px solid var(--ink-08);
  background: var(--paper);
}

/* 首屏框景 */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding-block: clamp(2rem, 5vw, 3.5rem) clamp(2.6rem, 6vw, 5rem);
  background: var(--deep);
  color: var(--paper-white);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--mist-16) 1px, transparent 1px),
    linear-gradient(to bottom, var(--mist-16) 1px, transparent 1px);
  background-size: 64px 64px;
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -28vw;
  right: -20vw;
  width: 62vw;
  height: 62vw;
  background: radial-gradient(circle, rgba(0, 216, 255, .26), transparent 62%);
  pointer-events: none;
}

.page-about .about-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 2rem;
}

.page-about .about-hero-copy h1 {
  margin: .9rem 0 0;
  max-width: 17ch;
  font-size: clamp(1.9rem, 5.4vw, 3.7rem);
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: .05em;
  color: var(--paper-white);
}

.page-about .about-lede {
  margin: 1.1rem 0 0;
  max-width: 48ch;
  font-size: clamp(.95rem, 1.6vw, 1.05rem);
  line-height: 1.85;
  color: var(--paper-72);
}

.page-about .about-hero-facts {
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--mist-32);
  border-top: 1px solid var(--mist-32);
}

.page-about .about-hero-facts li {
  display: flex;
  flex-direction: column;
  gap: .3rem;
  padding: .9rem 1rem .3rem 0;
  background: var(--deep);
}

.page-about .about-fact-num {
  font-size: clamp(1.4rem, 3.2vw, 2rem);
  line-height: 1;
  letter-spacing: .06em;
  color: var(--cyan);
}

.page-about .about-fact-label {
  font-size: .76rem;
  letter-spacing: .1em;
  color: var(--paper-72);
}

.page-about .about-hero-figure {
  margin: 0;
  padding: .5rem;
  border: 1px solid var(--mist-32);
  background: rgba(6, 26, 64, .55);
}

.page-about .about-hero-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.page-about .about-hero-figure figcaption {
  margin-top: .55rem;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--mist);
}

/* 双栏：左刻度 / 右档案流 */
.page-about .about-layout {
  display: grid;
  gap: 2.5rem;
  padding-block: clamp(2.4rem, 5vw, 4.5rem) clamp(3rem, 6vw, 5.5rem);
}

.page-about .about-rail-title {
  margin: 0 0 .9rem;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--ink-52);
}

.page-about .about-rail-list {
  list-style: none;
  margin: 0 0 1.5rem;
  padding: 0;
  display: flex;
  gap: .5rem;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail-list li {
  flex: 0 0 auto;
}

.page-about .about-rail-link {
  display: flex;
  align-items: baseline;
  gap: .55rem;
  padding: .45rem .7rem;
  border: 1px solid var(--ink-16);
  border-left: 2px solid transparent;
  font-size: .82rem;
  color: var(--ink-72);
  text-decoration: none;
  white-space: nowrap;
  transition: color .25s var(--ease), border-color .25s var(--ease), background .25s var(--ease);
}

.page-about .about-rail-link .mono {
  font-size: .7rem;
  letter-spacing: .1em;
  color: var(--ink-52);
}

.page-about .about-rail-link:hover {
  color: var(--cobalt);
  border-color: var(--cobalt);
  background: var(--paper-white);
}

.page-about .about-rail-link[aria-current="true"] {
  color: var(--cobalt);
  border-color: var(--ink-16);
  border-left-color: var(--cyan);
  background: var(--paper-white);
  font-weight: 600;
}

.page-about .about-rail-card {
  padding: 1.1rem;
  border-top: 2px solid var(--orange);
  background: var(--deep);
  color: var(--paper-white);
}

.page-about .about-rail-card-label {
  margin: 0 0 .4rem;
  font-size: .66rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--mist);
}

.page-about .about-rail-version {
  margin: 0 0 .5rem;
  font-family: var(--font-mono);
  font-size: 1.6rem;
  letter-spacing: .1em;
  color: var(--cyan);
}

.page-about .about-rail-card-text {
  margin: 0 0 1rem;
  font-size: .82rem;
  line-height: 1.8;
  color: var(--paper-72);
}

.page-about .about-rail-card .btn {
  display: inline-block;
  width: 100%;
  text-align: center;
}

/* 档案流 */
.page-about .about-flow {
  display: grid;
  gap: clamp(2.6rem, 5vw, 4.5rem);
  min-width: 0;
}

.page-about .about-section {
  position: relative;
  padding-top: 1.3rem;
  border-top: 1px solid var(--ink-16);
  min-width: 0;
}

.page-about .about-section-head {
  position: relative;
  padding-right: 1.8rem;
  margin-bottom: 1.1rem;
}

.page-about .about-section-index {
  margin: 0 0 .55rem;
  font-size: .76rem;
  letter-spacing: .18em;
  color: var(--cobalt);
}

.page-about .about-section-head h2 {
  margin: 0;
  max-width: 24ch;
  font-size: clamp(1.4rem, 3.6vw, 2.25rem);
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: .05em;
  color: var(--ink);
}

.page-about .about-section-note {
  position: absolute;
  top: 0;
  right: 0;
  writing-mode: vertical-rl;
  margin: 0;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .3em;
  color: var(--ink-24);
}

.page-about .about-lead {
  margin: 0 0 1.6rem;
  max-width: 62ch;
  font-size: clamp(.94rem, 1.5vw, 1.03rem);
  line-height: 1.86;
  color: var(--ink-72);
}

/* 三步方法 */
.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  border: 1px solid var(--ink-16);
  background: var(--ink-16);
}

.page-about .about-step {
  display: flex;
  flex-direction: column;
  gap: .55rem;
  padding: 1.2rem 1.1rem 1.4rem;
  background: var(--paper-white);
}

.page-about .about-step-num {
  position: relative;
  padding-bottom: .55rem;
  border-bottom: 1px solid var(--ink-08);
  font-size: .72rem;
  letter-spacing: .18em;
  color: var(--cobalt);
}

.page-about .about-step-num::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 26px;
  height: 2px;
  background: var(--cyan);
}

.page-about .about-step h3 {
  margin: 0;
  font-size: 1.05rem;
  letter-spacing: .06em;
  color: var(--ink);
}

.page-about .about-step p {
  margin: 0;
  font-size: .9rem;
  line-height: 1.8;
  color: var(--ink-72);
}

.page-about .about-tail {
  margin: 1.4rem 0 0;
  padding: .9rem 0 .9rem 1rem;
  max-width: 60ch;
  border-left: 2px solid var(--orange);
  font-size: .9rem;
  line-height: 1.82;
  color: var(--ink-72);
}

/* 版本与修订 */
.page-about .about-version-grid {
  display: grid;
  gap: 1px;
  border: 1px solid var(--ink-16);
  background: var(--ink-16);
}

.page-about .about-version-card {
  padding: 1.4rem 1.2rem;
  background: var(--deep);
  color: var(--paper-white);
}

.page-about .about-version-tag {
  margin: 0 0 .55rem;
  font-size: 1.5rem;
  letter-spacing: .12em;
  color: var(--cyan);
}

.page-about .about-version-card h3 {
  margin: 0 0 .5rem;
  font-size: 1rem;
  letter-spacing: .06em;
}

.page-about .about-version-card p {
  margin: 0;
  font-size: .88rem;
  line-height: 1.8;
  color: var(--paper-72);
}

.page-about .about-rhythm {
  list-style: none;
  margin: 0;
  padding: 0;
  background: var(--paper-white);
}

.page-about .about-rhythm li {
  display: grid;
  grid-template-columns: 5.2rem minmax(0, 1fr);
  gap: .7rem;
  padding: 1rem 1.2rem;
  border-bottom: 1px solid var(--ink-08);
  font-size: .88rem;
  line-height: 1.75;
  color: var(--ink-72);
}

.page-about .about-rhythm li:last-child {
  border-bottom: 0;
}

.page-about .about-rhythm .mono {
  font-size: .76rem;
  letter-spacing: .1em;
  color: var(--cobalt);
}

.page-about .about-check-flow {
  margin-top: 1rem;
  padding: 1.2rem;
  border: 1px dashed var(--ink-24);
  background: var(--paper-white);
}

.page-about .about-check-label {
  margin: 0 0 .9rem;
  font-size: .7rem;
  letter-spacing: .18em;
  color: var(--ink-52);
}

.page-about .about-check-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .85rem;
  counter-reset: chk;
}

.page-about .about-check-list li {
  position: relative;
  padding-left: 2.4rem;
  font-size: .9rem;
  line-height: 1.75;
  color: var(--ink-72);
  counter-increment: chk;
}

.page-about .about-check-list li::before {
  content: "0" counter(chk);
  position: absolute;
  left: 0;
  top: .18rem;
  padding: .05rem .3rem;
  border: 1px solid var(--ink-16);
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .06em;
  color: var(--cobalt);
}

/* 插图 */
.page-about .about-figure {
  margin: 0 0 1.5rem;
  padding: .5rem;
  border: 1px solid var(--ink-16);
  background: var(--deep);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about .about-figure figcaption {
  margin-top: .55rem;
  padding-inline: .2rem;
  font-family: var(--font-mono);
  font-size: .66rem;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--mist);
}

/* 团队 */
.page-about .about-teams {
  display: grid;
  gap: 1px;
  border: 1px solid var(--ink-16);
  background: var(--ink-16);
}

.page-about .about-team {
  background: var(--paper-white);
}

.page-about .about-team summary {
  display: flex;
  align-items: baseline;
  gap: .6rem;
  padding: 1rem 1.1rem;
  list-style: none;
  cursor: pointer;
  font-size: .98rem;
  font-weight: 700;
  letter-spacing: .05em;
  color: var(--ink);
}

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

.page-about .about-team summary::after {
  content: "＋";
  margin-left: auto;
  font-family: var(--font-mono);
  font-weight: 400;
  color: var(--cobalt);
}

.page-about .about-team[open] summary::after {
  content: "－";
}

.page-about .about-team summary .mono {
  font-size: .72rem;
  letter-spacing: .12em;
  color: var(--cobalt);
}

.page-about .about-team p {
  margin: 0;
  padding: 0 1.1rem 1.1rem;
  font-size: .88rem;
  line-height: 1.8;
  color: var(--ink-72);
}

/* 服务范围 */
.page-about .about-range-grid {
  display: grid;
  gap: 1.5rem;
}

.page-about .about-range-copy {
  min-width: 0;
}

.page-about .about-range-facts {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--ink-16);
}

.page-about .about-range-facts li {
  display: grid;
  gap: .2rem;
  padding: .85rem 0;
  border-bottom: 1px solid var(--ink-08);
  font-size: .9rem;
  line-height: 1.7;
  color: var(--ink-72);
}

.page-about .about-range-facts .mono {
  font-size: .84rem;
  letter-spacing: .1em;
  color: var(--cobalt);
}

.page-about .about-figure--range {
  margin-bottom: 0;
}

/* 长期承诺 */
.page-about .about-promise-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  border: 1px solid var(--ink-16);
  background: var(--ink-16);
}

.page-about .about-promise-list li {
  padding: 1.1rem 1.1rem;
  background: var(--paper-white);
  border-left: 2px solid var(--cobalt);
}

.page-about .about-promise-list h3 {
  margin: 0 0 .4rem;
  font-size: .98rem;
  letter-spacing: .06em;
  color: var(--ink);
}

.page-about .about-promise-list p {
  margin: 0;
  font-size: .88rem;
  line-height: 1.78;
  color: var(--ink-72);
}

.page-about .about-cta {
  margin-top: 1.6rem;
  padding: 1.4rem 1.2rem;
  border-top: 2px solid var(--cyan);
  background: var(--deep);
  color: var(--paper-white);
}

.page-about .about-cta p {
  margin: 0 0 1.1rem;
  max-width: 46ch;
  font-size: .94rem;
  line-height: 1.8;
  color: var(--paper-72);
}

.page-about .about-cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: .7rem;
}

/* 断点：平板与桌面 */
@media (min-width: 640px) {
  .page-about .about-hero-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .about-steps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-version-grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

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

@media (min-width: 860px) {
  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: end;
    gap: 3rem;
  }

  .page-about .about-teams {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-range-grid {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    align-items: start;
    gap: 2rem;
  }
}

@media (min-width: 960px) {
  .page-about .about-layout {
    grid-template-columns: 220px minmax(0, 1fr);
    gap: clamp(2rem, 4vw, 4rem);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 5.5rem;
  }

  .page-about .about-rail-list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
  }

  .page-about .about-rail-link {
    border: 0;
    border-left: 2px solid transparent;
    padding: .6rem .4rem .6rem .8rem;
    font-size: .88rem;
  }

  .page-about .about-rail-link:hover,
  .page-about .about-rail-link[aria-current="true"] {
    border-left-color: var(--cyan);
    background: var(--paper-white);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail-link {
    transition: none;
  }
}