.page-about {
  --about-chamfer: 16px;
  --about-panel-grad: linear-gradient(155deg, rgba(19, 28, 43, 0.92), rgba(13, 20, 32, 0.96));
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: clamp(104px, 16vh, 168px) 0 clamp(40px, 6vw, 72px);
  overflow: hidden;
  isolation: isolate;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(58% 46% at 78% 10%, rgba(41, 242, 184, 0.13), transparent 66%),
    radial-gradient(52% 44% at 6% 92%, rgba(109, 124, 255, 0.12), transparent 70%);
  pointer-events: none;
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(28px, 4vw, 48px);
  align-items: center;
}

.page-about .about-hero__lead h1 {
  margin: 14px 0 20px;
  font-family: var(--font-head);
  font-size: clamp(34px, 5.4vw, 66px);
  font-weight: 900;
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .about-hero__lead .lede {
  max-width: 62ch;
  color: var(--text-dim);
  font-size: clamp(15px, 1.15vw, 17px);
  line-height: 1.8;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

/* 首屏仪表视觉 */
.page-about .about-hero__gauge {
  position: relative;
  padding: 20px 20px 14px;
  background: var(--about-panel-grad);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - var(--about-chamfer)) 0, 100% var(--about-chamfer), 100% 100%, var(--about-chamfer) 100%, 0 calc(100% - var(--about-chamfer)));
}

.page-about .gauge__cap {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-dim);
}

.page-about .gauge__wave {
  display: block;
  width: 100%;
  height: clamp(110px, 16vw, 168px);
}

.page-about .gauge__ticks {
  height: 22px;
  margin-top: 10px;
  background-image: repeating-linear-gradient(to right, var(--line) 0 1px, transparent 1px 4%);
  background-size: 100% 100%;
  border-top: 1px solid var(--line);
}

.page-about .gauge__scale {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--text-dim);
  opacity: 0.8;
}

/* 首屏数据条 */
.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(36px, 5vw, 64px) 0 0;
  padding: 0;
  list-style: none;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-hero__stats li {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 20px 18px;
  background: var(--bg);
}

.page-about .stat-val {
  font-family: var(--font-mono);
  font-size: clamp(24px, 3vw, 34px);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--accent);
  letter-spacing: -0.01em;
}

.page-about .stat-key {
  color: var(--text-dim);
}

/* ---------- 通用区块标题微调 ---------- */
.page-about .section__head h2 {
  margin: 12px 0 14px;
  font-family: var(--font-head);
  font-size: clamp(25px, 3.1vw, 38px);
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .section__head .lede {
  max-width: 68ch;
  color: var(--text-dim);
  line-height: 1.8;
}

/* ---------- 问题区 ---------- */
.page-about .about-problems__grid {
  display: grid;
  gap: clamp(20px, 3vw, 32px);
  margin-top: clamp(28px, 4vw, 48px);
}

.page-about .problem-card {
  position: relative;
  padding-top: 22px;
  border-top: 2px solid var(--line);
  transition: border-color 0.25s ease;
}

.page-about .problem-card:hover,
.page-about .problem-card:focus-within {
  border-top-color: var(--accent);
}

.page-about .problem-card__idx {
  display: inline-block;
  margin-bottom: 10px;
  font-size: 13px;
  letter-spacing: 0.18em;
  color: var(--accent-dim);
}

.page-about .problem-card h3 {
  margin: 0 0 12px;
  font-family: var(--font-head);
  font-size: clamp(18px, 1.6vw, 22px);
  font-weight: 800;
  color: var(--text);
}

.page-about .problem-card p {
  margin: 0 0 12px;
  color: var(--text-dim);
  line-height: 1.78;
}

.page-about .problem-card__foot {
  font-size: 14px;
  color: var(--text);
  opacity: 0.78;
  border-left: 2px solid var(--accent-dim);
  padding-left: 12px;
}

/* ---------- 测量方法 ---------- */
.page-about .about-method__grid {
  display: grid;
  gap: clamp(22px, 3vw, 36px);
  margin-top: clamp(28px, 4vw, 48px);
}

.page-about .about-method__spec h3,
.page-about .about-method__metrics h3 {
  margin: 0 0 16px;
  font-family: var(--font-head);
  font-size: clamp(18px, 1.6vw, 22px);
  font-weight: 800;
  color: var(--text);
}

.page-about .spec-list {
  margin: 0;
}

.page-about .spec {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .spec dt {
  color: var(--text-dim);
  font-size: 14px;
}

.page-about .spec dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--text);
  text-align: right;
}

.page-about .about-method__hint {
  margin: 18px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-dim);
}

.page-about .about-method__sub {
  margin: -8px 0 18px;
  font-size: 14px;
  color: var(--text-dim);
}

.page-about .metric {
  border-bottom: 1px solid var(--line-soft);
}

.page-about .metric summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 15px 0;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-head);
  font-size: 16px;
  font-weight: 700;
  color: var(--text);
  transition: color 0.2s ease;
}

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

.page-about .metric summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--accent-dim);
  transition: color 0.2s ease;
}

.page-about .metric[open] summary {
  color: var(--accent);
}

.page-about .metric[open] summary::after {
  content: "−";
  color: var(--accent);
}

.page-about .metric summary:hover::after {
  color: var(--accent);
}

.page-about .metric__unit {
  margin-left: auto;
  padding-right: 14px;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--text-dim);
}

.page-about .metric__body {
  padding: 0 0 18px;
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
  animation: aboutFade 0.18s ease both;
}

@keyframes aboutFade {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* ---------- 线路覆盖 ---------- */
.page-about .about-coverage__grid {
  display: grid;
  gap: clamp(26px, 4vw, 52px);
  align-items: start;
}

.page-about .about-coverage__text h2 {
  margin: 12px 0 14px;
  font-family: var(--font-head);
  font-size: clamp(25px, 3.1vw, 38px);
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .about-coverage__text .lede {
  max-width: 60ch;
  margin-bottom: 26px;
  color: var(--text-dim);
  line-height: 1.8;
}

.page-about .line-bars {
  display: grid;
  gap: 20px;
}

.page-about .line-bar__meta {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 8px;
}

.page-about .line-bar__meta .mono {
  font-size: 12px;
  color: var(--text-dim);
}

.page-about .line-bar__track {
  height: 12px;
  background: var(--panel);
  border: 1px solid var(--line);
  overflow: hidden;
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 100%, 0 100%);
}

.page-about .line-bar__fill {
  height: 100%;
  transition: filter 0.25s ease;
}

.page-about .line-bar--a .line-bar__fill { width: 100%; background: linear-gradient(90deg, var(--accent-dim), var(--accent)); }
.page-about .line-bar--b .line-bar__fill { width: 82%; background: linear-gradient(90deg, rgba(109, 124, 255, 0.55), var(--violet)); }
.page-about .line-bar--c .line-bar__fill { width: 72%; background: linear-gradient(90deg, var(--accent-dim), var(--accent)); }
.page-about .line-bar--d .line-bar__fill { width: 46%; background: linear-gradient(90deg, rgba(109, 124, 255, 0.4), var(--violet)); }

.page-about .line-bar:hover .line-bar__fill {
  filter: brightness(1.4);
}

.page-about .line-bar__desc {
  margin: 8px 0 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--text-dim);
}

.page-about .about-coverage__note {
  margin: 26px 0 0;
  padding-left: 14px;
  border-left: 2px solid var(--line);
  font-size: 14px;
  line-height: 1.78;
  color: var(--text-dim);
}

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

.page-about .about-coverage__figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 1 / 1;
  object-fit: cover;
  border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - var(--about-chamfer)) 0, 100% var(--about-chamfer), 100% 100%, 0 100%);
}

.page-about .about-coverage__figure figcaption {
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--text-dim);
}

/* ---------- 时间轴 ---------- */
.page-about .about-timeline {
  position: relative;
  overflow: hidden;
  isolation: isolate;
}

.page-about .about-timeline__texture {
  position: absolute;
  inset: 0;
  z-index: -1;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.32;
  pointer-events: none;
}

.page-about .about-timeline__inner {
  position: relative;
}

.page-about .timeline__list {
  position: relative;
  display: grid;
  gap: 16px;
  margin: clamp(28px, 4vw, 48px) 0 0;
  padding: 0 0 0 26px;
  list-style: none;
}

.page-about .timeline__list::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--accent), var(--accent-dim) 46%, rgba(41, 242, 184, 0));
}

.page-about .timeline__item {
  position: relative;
  padding: 18px 20px;
  background: var(--about-panel-grad);
  border: 1px solid var(--line);
  border-left: 2px solid var(--accent-dim);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 14px, 100% 100%, 0 100%);
  transition: border-color 0.25s ease, background 0.25s ease;
}

.page-about .timeline__item:hover,
.page-about .timeline__item:focus-within {
  border-color: var(--accent);
  background: linear-gradient(155deg, rgba(19, 28, 43, 0.98), rgba(13, 20, 32, 0.98));
}

.page-about .timeline__year {
  display: inline-block;
  margin-bottom: 8px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--accent);
}

.page-about .timeline__item h3 {
  margin: 0 0 10px;
  font-family: var(--font-head);
  font-size: clamp(17px, 1.5vw, 20px);
  font-weight: 800;
  color: var(--text);
}

.page-about .timeline__item p {
  margin: 0 0 10px;
  font-size: 15px;
  line-height: 1.76;
  color: var(--text-dim);
}

.page-about .timeline__note {
  margin: 0;
  font-size: 13px;
  color: var(--text);
  opacity: 0.68;
  transition: opacity 0.25s ease;
}

.page-about .timeline__item:hover .timeline__note,
.page-about .timeline__item:focus-within .timeline__note {
  opacity: 1;
}

/* ---------- 团队 ---------- */
.page-about .about-team__figure {
  margin: 0 0 clamp(28px, 4vw, 52px);
}

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

.page-about .about-team__facts {
  display: grid;
  gap: clamp(22px, 3vw, 36px);
  margin-top: clamp(26px, 4vw, 44px);
}

.page-about .fact {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
}

.page-about .fact__num {
  font-family: var(--font-mono);
  font-size: clamp(38px, 5vw, 56px);
  font-weight: 700;
  line-height: 1;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.03em;
  color: var(--accent);
}

.page-about .fact__key {
  color: var(--text-dim);
}

.page-about .fact p {
  margin: 8px 0 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
}

.page-about .about-team__extra {
  display: grid;
  gap: 20px;
  margin-top: clamp(30px, 4vw, 52px);
}

.page-about .extra-item h3 {
  margin: 0 0 8px;
  font-family: var(--font-head);
  font-size: 17px;
  font-weight: 800;
  color: var(--text);
}

.page-about .extra-item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
}

/* ---------- 选择理由 ---------- */
.page-about .about-reasons__grid {
  display: grid;
  gap: clamp(20px, 3vw, 32px);
  margin-top: clamp(28px, 4vw, 48px);
}

.page-about .reason {
  position: relative;
  padding: 24px 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, calc(100% - var(--about-chamfer)) 0, 100% var(--about-chamfer), 100% 100%, 0 100%);
  transition: border-color 0.25s ease, background 0.25s ease;
}

.page-about .reason:hover,
.page-about .reason:focus-within {
  border-color: var(--accent-dim);
  background: var(--panel-2);
}

.page-about .reason__idx {
  display: inline-block;
  margin-bottom: 12px;
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--accent);
}

.page-about .reason h3 {
  margin: 0 0 12px;
  font-family: var(--font-head);
  font-size: clamp(18px, 1.6vw, 21px);
  font-weight: 800;
  color: var(--text);
}

.page-about .reason p {
  margin: 0 0 18px;
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
}

.page-about .reason__link {
  display: inline-block;
  position: relative;
  font-size: 14px;
  font-weight: 700;
  color: var(--accent);
  text-decoration: none;
  padding-bottom: 2px;
}

.page-about .reason__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 1px;
  background: var(--accent);
  transition: width 0.28s ease;
}

.page-about .reason__link:hover::after,
.page-about .reason__link:focus-visible::after {
  width: 100%;
}

.page-about .about-reasons__cta {
  display: flex;
  flex-direction: column;
  gap: 18px;
  margin-top: clamp(30px, 4vw, 52px);
  padding: 26px 22px;
  background: linear-gradient(120deg, rgba(14, 127, 99, 0.22), rgba(13, 20, 32, 0.9) 62%);
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent);
}

.page-about .about-reasons__cta p {
  margin: 0;
  max-width: 66ch;
  font-size: 16px;
  line-height: 1.78;
  color: var(--text);
}

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

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

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

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

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

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: 7fr 5fr;
  }

  .page-about .about-method__grid {
    grid-template-columns: 5fr 7fr;
  }

  .page-about .about-coverage__grid {
    grid-template-columns: 7fr 5fr;
  }

  /* 斜向时间轴 */
  .page-about .timeline__list {
    padding-left: 0;
    gap: 10px;
  }

  .page-about .timeline__list::before {
    left: 50%;
    top: -10px;
    bottom: -10px;
    width: 2px;
    transform: rotate(7deg);
    transform-origin: center center;
  }

  .page-about .timeline__item {
    width: 46%;
  }

  .page-about .timeline__item:nth-child(odd) {
    justify-self: start;
    border-left: 1px solid var(--line);
    border-right: 2px solid var(--accent-dim);
    clip-path: polygon(var(--about-chamfer) 0, 100% 0, 100% 100%, 0 100%, 0 var(--about-chamfer));
    text-align: right;
  }

  .page-about .timeline__item:nth-child(odd):hover {
    border-right-color: var(--accent);
  }

  .page-about .timeline__item:nth-child(even) {
    justify-self: end;
  }

  .page-about .timeline__item:nth-child(n + 3) {
    margin-top: 6px;
  }
}

@media (min-width: 1200px) {
  .page-about .about-hero__grid {
    grid-template-columns: 7fr 5fr;
    gap: 64px;
  }

  .page-about .timeline__item {
    width: 44%;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    animation: none !important;
    transition: none !important;
  }
}