.page-about {
  --about-rail-w: 15rem;
  --about-line: rgba(74, 102, 124, 0.34);
  --about-line-strong: rgba(33, 26, 22, 0.22);
  --about-paper: rgba(255, 255, 255, 0.55);
  --about-text: rgba(33, 26, 22, 0.84);
  background: var(--ink);
  color: var(--mist-soft);
}

.page-about figure {
  margin: 0;
}

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

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(1rem, 3vw, 1.75rem) clamp(2rem, 5vw, 3.75rem);
  border-bottom: 1px solid var(--hair);
  background-color: var(--ink);
  background-image:
    repeating-linear-gradient(90deg, rgba(74, 102, 124, 0.22) 0 1px, transparent 1px 88px),
    linear-gradient(180deg, rgba(16, 43, 64, 0.72) 0%, rgba(8, 24, 38, 0.96) 88%);
}

.page-about .breadcrumbs {
  font-size: 0.75rem;
  color: var(--mist-dim);
}

.page-about .breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .breadcrumbs li + li::before {
  content: "/";
  margin-right: 0.4rem;
  color: var(--slate);
}

.page-about .breadcrumbs a {
  color: var(--mist-dim);
  text-decoration: none;
}

.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-coords {
  margin: 1rem 0 1.5rem;
  padding-top: 0.7rem;
  border-top: 1px solid var(--hair-soft);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .about-hero__lead .section-label {
  color: var(--cyan);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  margin: 0 0 0.75rem;
}

.page-about .about-hero__lead h1 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.75rem, 5.4vw, 3rem);
  line-height: 1.18;
  letter-spacing: -0.015em;
  color: var(--cream);
}

.page-about .about-hero__intro {
  margin: 1.1rem 0 0;
  max-width: 46ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--mist-soft);
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 1.75rem 0 0;
  padding: 0;
  list-style: none;
  background: var(--hair-soft);
  border: 1px solid var(--hair-soft);
}

.page-about .about-hero__facts li {
  display: grid;
  gap: 0.3rem;
  align-content: start;
  padding: 0.85rem;
  background: rgba(16, 43, 64, 0.82);
}

.page-about .about-fact__num {
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.1;
  color: var(--cyan);
}

.page-about .about-fact__label {
  font-size: 0.78rem;
  line-height: 1.55;
  color: var(--mist-dim);
}

/* ---------- 正文纸面 ---------- */
.page-about .about-doc {
  background: var(--cream);
  color: var(--brown);
  padding-block: clamp(1.75rem, 4vw, 3.5rem);
}

.page-about .about-doc__inner {
  display: grid;
  gap: clamp(1.5rem, 3vw, 2.5rem);
}

/* 章节索引 */
.page-about .about-rail {
  border-top: 2px solid var(--brown);
  padding-top: 0.85rem;
}

.page-about .about-rail__title {
  margin: 0 0 0.85rem;
  font-size: 0.68rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--slate);
}

.page-about .about-rail__list {
  display: grid;
  gap: 0.1rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-rail__list a {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  padding: 0.5rem 0.1rem;
  border-bottom: 1px solid rgba(33, 26, 22, 0.14);
  color: var(--brown);
  font-size: 0.9rem;
  text-decoration: none;
  transition: color 180ms ease, border-color 180ms ease;
}

.page-about .about-rail__list a .mono {
  font-size: 0.72rem;
  color: var(--orange);
}

.page-about .about-rail__list a:hover,
.page-about .about-rail__list a:focus-visible {
  color: var(--orange);
  border-bottom-color: var(--orange);
}

.page-about .about-rail__note {
  margin: 1rem 0 0;
  font-size: 0.8rem;
  line-height: 1.7;
  color: var(--slate);
}

.page-about .about-rail__note a {
  color: var(--brown);
  text-decoration: underline;
  text-decoration-color: var(--orange);
  text-underline-offset: 3px;
}

/* 章节 */
.page-about .about-section {
  padding-block: clamp(1.5rem, 3.5vw, 2.5rem);
  border-top: 1px solid var(--about-line);
}

.page-about .about-section:first-child {
  padding-top: 0;
  border-top: 0;
}

.page-about .about-section .section-label {
  margin: 0 0 0.6rem;
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  color: var(--orange);
}

.page-about .about-section h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.35rem, 3.1vw, 2rem);
  line-height: 1.3;
  letter-spacing: -0.01em;
  color: var(--brown);
}

.page-about .about-section__body {
  display: grid;
  gap: clamp(1rem, 2.5vw, 1.5rem);
  margin-top: 1.1rem;
}

.page-about .about-prose p {
  margin: 0 0 0.95rem;
  font-size: 0.98rem;
  line-height: 1.9;
  color: var(--about-text);
  overflow-wrap: anywhere;
}

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

.page-about .about-lead {
  margin: 1rem 0 0;
  max-width: 62ch;
  font-size: 0.96rem;
  line-height: 1.85;
  color: var(--about-text);
}

/* 三点问题 */
.page-about .about-points {
  display: grid;
  gap: 1px;
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
  background: var(--about-line);
  border: 1px solid var(--about-line);
}

.page-about .about-points li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.85rem;
  padding: 0.95rem 1rem;
  background: var(--about-paper);
}

.page-about .about-points .mono {
  font-size: 0.78rem;
  color: var(--orange);
  letter-spacing: 0.1em;
}

.page-about .about-points strong {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 0.98rem;
  color: var(--brown);
}

.page-about .about-points p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.78;
  color: var(--about-text);
}

/* 方法双栏 */
.page-about .about-method {
  display: grid;
  gap: clamp(1rem, 2.5vw, 1.6rem);
  align-items: start;
}

/* STEP 提示 */
.page-about .about-step-note {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.9rem;
  align-items: start;
  padding: 1rem 1.1rem;
  border: 1px solid var(--about-line-strong);
  border-left: 3px solid var(--orange);
  background: rgba(241, 120, 60, 0.09);
}

.page-about .about-step-note__num {
  padding-top: 0.15rem;
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  color: var(--orange);
}

.page-about .about-step-note p {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.8;
  color: rgba(33, 26, 22, 0.88);
}

/* 维护节奏表 */
.page-about .about-cadence-wrap {
  overflow-x: auto;
  border: 1px solid var(--about-line);
}

.page-about .about-cadence {
  width: 100%;
  min-width: 20rem;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.page-about .about-cadence caption {
  padding: 0.7rem 0.85rem;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  color: var(--slate);
  background: rgba(74, 102, 124, 0.14);
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-cadence th,
.page-about .about-cadence td {
  padding: 0.7rem 0.85rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-cadence thead th {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--slate);
  background: rgba(74, 102, 124, 0.1);
}

.page-about .about-cadence tbody tr:last-child td {
  border-bottom: 0;
}

.page-about .about-cadence td.mono {
  white-space: nowrap;
  color: var(--orange);
  font-size: 0.78rem;
}

.page-about .about-cadence td:last-child {
  color: var(--about-text);
  line-height: 1.7;
}

/* 团队 */
.page-about .about-team {
  display: grid;
  gap: 1px;
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
  background: var(--about-line);
  border: 1px solid var(--about-line);
}

.page-about .about-team__card {
  padding: 1rem 1.05rem 1.15rem;
  background: var(--about-paper);
}

.page-about .about-team__index {
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  color: var(--orange);
}

.page-about .about-team__card h3 {
  margin: 0.4rem 0 0.45rem;
  font-family: var(--font-display);
  font-size: 1.05rem;
  color: var(--brown);
}

.page-about .about-team__card p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.78;
  color: var(--about-text);
}

/* 时间轴与分段切换 */
.page-about .about-history {
  display: grid;
  gap: clamp(1.25rem, 3vw, 1.75rem);
  margin-top: 1.25rem;
  align-items: start;
}

.page-about .about-tabs .tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin: 0 0 1.25rem;
}

.page-about .about-tabs .tabs__tab {
  appearance: none;
  padding: 0.5rem 0.8rem;
  border: 1px solid var(--about-line-strong);
  border-radius: 0;
  background: transparent;
  color: var(--brown);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: background-color 200ms ease, color 200ms ease, border-color 200ms ease;
}

.page-about .about-tabs .tabs__tab:hover {
  border-color: var(--orange);
}

.page-about .about-tabs .tabs__tab[aria-selected="true"] {
  background: var(--brown);
  border-color: var(--brown);
  color: var(--cream);
}

.page-about .about-tabs .tabs__tab[aria-selected="true"]:hover {
  color: var(--cream);
}

.page-about .about-tabs .tabs__tab:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 2px;
}

.page-about .about-timeline {
  display: grid;
  gap: 1.25rem;
  margin: 0;
  padding: 0 0 0 1.25rem;
  list-style: none;
  border-left: 1px solid var(--about-line);
}

.page-about .about-timeline li {
  position: relative;
}

.page-about .about-timeline li::before {
  content: "";
  position: absolute;
  top: 0.45rem;
  left: -1.32rem;
  width: 9px;
  height: 9px;
  background: var(--orange);
}

.page-about .about-timeline__meta {
  margin: 0;
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  color: var(--orange);
}

.page-about .about-timeline h3 {
  margin: 0.2rem 0 0.35rem;
  font-family: var(--font-display);
  font-size: 0.98rem;
  color: var(--brown);
}

.page-about .about-timeline p:last-child {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.8;
  color: var(--about-text);
}

/* 数据块 */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 1.25rem 0 0;
  padding: 0;
  list-style: none;
  background: var(--hair);
  border: 1px solid var(--hair);
}

.page-about .about-stats li {
  display: grid;
  gap: 0.3rem;
  align-content: start;
  padding: 1rem;
  background: var(--ink-2);
}

.page-about .about-stats__num {
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 3.4vw, 2rem);
  font-weight: 700;
  line-height: 1;
  color: var(--orange);
}

.page-about .about-stats__unit {
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--mint);
}

.page-about .about-stats li p {
  margin: 0.2rem 0 0;
  font-size: 0.8rem;
  line-height: 1.65;
  color: var(--mist-dim);
}

/* 原则手风琴 */
.page-about .about-principles {
  display: grid;
  gap: 0.65rem;
  margin: 1.5rem 0 0;
}

.page-about .about-principle {
  border: 1px solid var(--about-line-strong);
  background: var(--about-paper);
}

.page-about .about-principle summary {
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
  padding: 0.85rem 1rem;
  font-family: var(--font-display);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--brown);
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-principle summary .mono {
  font-size: 0.7rem;
  font-weight: 400;
  letter-spacing: 0.1em;
  color: var(--orange);
}

.page-about .about-principle summary:hover {
  color: var(--orange);
}

.page-about .about-principle summary:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: -2px;
}

.page-about .about-principle[open] summary {
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-principle__body {
  padding: 0.85rem 1rem 1rem;
}

.page-about .about-principle__body p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.85;
  color: var(--about-text);
}

/* 备案说明 */
.page-about .about-legal {
  margin: 1.5rem 0 0;
  padding-top: 0.9rem;
  border-top: 1px solid var(--about-line-strong);
  font-size: 0.84rem;
  line-height: 1.85;
  color: rgba(33, 26, 22, 0.78);
}

.page-about .about-legal a {
  color: var(--brown);
  text-decoration: underline;
  text-decoration-color: var(--orange);
  text-underline-offset: 3px;
}

/* 下一步 */
.page-about .about-next {
  display: grid;
  gap: 0.75rem;
  margin-top: clamp(1.75rem, 4vw, 2.75rem);
  padding: clamp(1.25rem, 3vw, 2rem);
  border-left: 4px solid var(--orange);
  background: var(--ink);
  color: var(--cream);
}

.page-about .about-next__label {
  margin: 0;
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-next h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 2.8vw, 1.7rem);
  line-height: 1.3;
  color: var(--cream);
}

.page-about .about-next p {
  margin: 0;
  font-size: 0.94rem;
  line-height: 1.8;
  color: var(--mist-soft);
}

.page-about .about-next__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 0.35rem;
}

.page-about .about-next__links {
  font-size: 0.84rem;
  color: var(--mist-dim);
}

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

.page-about .about-next__links a:hover,
.page-about .about-next__links a:focus-visible {
  color: var(--cream);
}

/* ---------- 桌面布局 ---------- */
@media (min-width: 46rem) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.95fr);
    gap: clamp(1.75rem, 4vw, 3rem);
    align-items: start;
  }

  .page-about .about-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .about-method {
    grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
  }

  .page-about .about-history {
    grid-template-columns: minmax(0, 1.12fr) minmax(0, 0.88fr);
  }
}

@media (min-width: 62rem) {
  .page-about .about-doc__inner {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(2rem, 4vw, 4rem);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 1.25rem);
  }

  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-section__body {
    gap: 1.6rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__list a,
  .page-about .about-tabs .tabs__tab {
    transition: none;
  }
}