.page-about {
  --about-line: rgba(217, 222, 232, 0.22);
  --about-line-soft: rgba(217, 222, 232, 0.12);
  background: var(--ink);
  color: var(--paper);
}

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

/* 面包屑 */
.page-about .crumbs {
  padding: clamp(16px, 3vw, 28px) 0 0;
}

.page-about .crumbs ol {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4em;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--mist);
}

.page-about .crumbs li + li::before {
  content: "／";
  margin-right: 0.4em;
  color: rgba(147, 162, 196, 0.6);
}

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

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

.page-about .crumbs [aria-current="page"] {
  color: var(--paper);
}

/* 首屏 */
.page-about .about-hero {
  padding: clamp(26px, 5vw, 60px) 0 clamp(32px, 6vw, 76px);
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-hero-grid {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
}

.page-about .about-eyebrow {
  margin: 0 0 clamp(14px, 2vw, 20px);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--orange);
}

.page-about .about-hero h1 {
  margin: 0;
  font-size: clamp(36px, 9vw, 92px);
  line-height: 0.96;
  letter-spacing: -0.02em;
  font-weight: 800;
}

.page-about .about-lead {
  max-width: 42em;
  margin: clamp(18px, 3vw, 28px) 0 0;
  font-size: clamp(16px, 2.1vw, 18px);
  line-height: 1.75;
  color: var(--mist);
}

.page-about .about-hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 32px;
  margin: 0;
  padding-top: 18px;
  border-top: 1px solid var(--about-line);
}

.page-about .about-hero-meta dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--mist);
}

.page-about .about-hero-meta dd {
  margin: 8px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(20px, 3vw, 26px);
  font-weight: 500;
  color: var(--paper);
}

/* 章节通用 */
.page-about .about-sec {
  padding: clamp(38px, 7vw, 88px) 0;
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-sec-head h2 {
  margin: 0;
  font-size: clamp(24px, 4.2vw, 44px);
  line-height: 1.06;
  letter-spacing: -0.015em;
  font-weight: 800;
}

.page-about .about-sec-idx {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--orange);
}

.page-about .about-sec-note {
  margin: 14px 0 0;
  max-width: 36em;
  font-size: 14px;
  line-height: 1.65;
  color: var(--mist);
}

/* 起点 */
.page-about .about-origin-grid {
  display: grid;
  gap: clamp(20px, 3vw, 36px);
}

.page-about .about-origin-body p {
  margin: 0 0 1em;
  max-width: 38em;
  font-size: clamp(15px, 2vw, 17px);
  line-height: 1.78;
  color: var(--paper);
}

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

/* 历程 */
.page-about .about-timeline-figure,
.page-about .about-method-figure,
.page-about .about-team-figure {
  margin: 0;
}

.page-about .about-timeline-figure {
  margin: clamp(22px, 3.5vw, 36px) 0 clamp(28px, 4.5vw, 48px);
}

.page-about .about-timeline-figure img,
.page-about .about-method-figure img,
.page-about .about-team-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--about-line);
  background: var(--indigo);
  object-fit: cover;
}

.page-about .about-method-figure figcaption,
.page-about .about-team-figure figcaption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  color: var(--mist);
}

.page-about .stage-list {
  position: relative;
  display: grid;
  gap: clamp(20px, 3vw, 30px);
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .stage-list::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: var(--about-line);
}

.page-about .stage-row {
  display: grid;
  gap: 12px;
}

.page-about .stage-year {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 12px;
  padding-left: 22px;
  text-decoration: none;
  color: var(--paper);
}

.page-about .stage-dot {
  position: absolute;
  left: 1px;
  top: 0.42em;
  width: 9px;
  height: 9px;
  background: var(--indigo);
  border: 1px solid var(--mist);
}

.page-about .stage-row:last-child .stage-dot {
  background: var(--lime);
  border-color: var(--lime);
}

.page-about .stage-year-num {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: 0.08em;
  color: var(--paper);
}

.page-about .stage-year-note {
  font-size: 12px;
  line-height: 1.5;
  color: var(--mist);
  max-height: 4em;
  opacity: 1;
  transition: opacity 160ms var(--ease);
}

.page-about .stage-board {
  position: relative;
  max-width: 100%;
  padding: clamp(16px, 3vw, 26px) clamp(16px, 3vw, 28px);
  background: var(--paper);
  color: var(--indigo);
  border: 1px solid var(--rule);
  box-shadow: 6px 6px 0 var(--shade);
  transition: transform 180ms var(--ease), box-shadow 180ms var(--ease),
    border-color 180ms var(--ease);
}

.page-about .stage-idx {
  display: block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--blue);
}

.page-about .stage-board h3 {
  margin: 0 0 8px;
  font-size: clamp(17px, 2.4vw, 22px);
  line-height: 1.28;
  letter-spacing: -0.01em;
  font-weight: 800;
}

.page-about .stage-board p {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--indigo);
}

.page-about .stage-row:hover .stage-board,
.page-about .stage-row:focus-within .stage-board {
  transform: translateY(-3px);
  border-color: var(--blue);
  box-shadow: 10px 10px 0 var(--shade);
}

/* 方法论 */
.page-about .about-method-grid {
  display: grid;
  gap: clamp(22px, 3.5vw, 40px);
}

.page-about .method-list {
  display: grid;
  gap: clamp(14px, 2.4vw, 20px);
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .method-item {
  padding: clamp(16px, 2.6vw, 24px);
  background: var(--indigo);
  border: 1px solid var(--about-line);
  border-left: 3px solid var(--blue);
}

.page-about .method-num {
  display: block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--orange);
}

.page-about .method-item h3 {
  margin: 0 0 8px;
  font-size: clamp(17px, 2.2vw, 20px);
  line-height: 1.3;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .method-item p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

/* 团队 */
.page-about .team-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: clamp(22px, 3.5vw, 34px) 0 clamp(24px, 4vw, 40px);
  padding: 1px;
  list-style: none;
  background: var(--about-line);
}

.page-about .team-stats li {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: clamp(14px, 2.6vw, 22px);
  background: var(--ink);
}

.page-about .team-num {
  font-family: var(--font-sans);
  font-size: clamp(38px, 7vw, 66px);
  font-weight: 800;
  line-height: 0.9;
  letter-spacing: -0.02em;
  color: var(--paper);
}

.page-about .team-stats li:first-child .team-num {
  color: var(--orange);
}

.page-about .team-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--mist);
}

.page-about .about-team-grid {
  display: grid;
  gap: clamp(20px, 3.5vw, 36px);
}

.page-about .about-team-copy p {
  margin: 0 0 1em;
  max-width: 38em;
  font-size: clamp(15px, 2vw, 17px);
  line-height: 1.78;
  color: var(--paper);
}

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

/* 承诺 */
.page-about .about-promise {
  border-bottom: none;
}

.page-about .promise-list {
  margin: clamp(22px, 3.5vw, 34px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .promise-list li {
  position: relative;
  padding: clamp(15px, 2.6vw, 22px) 0 clamp(15px, 2.6vw, 22px) 26px;
  border-top: 1px solid var(--about-line);
  font-size: clamp(15px, 2vw, 17px);
  line-height: 1.72;
  color: var(--mist);
}

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

.page-about .promise-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: calc(clamp(15px, 2.6vw, 22px) + 0.62em);
  width: 9px;
  height: 9px;
  background: var(--lime);
}

.page-about .promise-list strong {
  color: var(--paper);
  font-weight: 700;
}

.page-about .about-next {
  margin-top: clamp(26px, 4vw, 44px);
  padding: clamp(18px, 3vw, 28px);
  background: var(--indigo);
  border: 1px solid var(--about-line);
  border-left: 3px solid var(--blue);
}

.page-about .about-next-title {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--orange);
}

.page-about .about-next ul {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-next a {
  display: inline-block;
  padding: 7px 13px;
  border: 1px solid var(--rule-mid);
  font-size: 14px;
  line-height: 1.3;
  color: var(--paper);
  text-decoration: none;
  transition: border-color 160ms var(--ease), color 160ms var(--ease);
}

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

/* 断点：平板起 */
@media (min-width: 640px) {
  .page-about .stage-row {
    grid-template-columns: 148px minmax(0, 1fr);
    align-items: start;
    gap: 18px;
  }

  .page-about .stage-year {
    padding-left: 24px;
    flex-direction: column;
    gap: 4px;
  }

  .page-about .stage-year-note {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: opacity 180ms var(--ease), max-height 180ms var(--ease);
  }

  .page-about .stage-row:hover .stage-year-note,
  .page-about .stage-row:focus-within .stage-year-note {
    max-height: 4em;
    opacity: 1;
  }

  .page-about .stage-row:nth-child(1) .stage-board {
    max-width: 100%;
  }

  .page-about .stage-row:nth-child(2) .stage-board {
    max-width: 88%;
  }

  .page-about .stage-row:nth-child(3) .stage-board {
    max-width: 76%;
  }

  .page-about .stage-row:nth-child(4) .stage-board {
    max-width: 68%;
  }

  .page-about .stage-row:nth-child(5) .stage-board {
    max-width: 60%;
  }

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

/* 断点：桌面 */
@media (min-width: 960px) {
  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 1fr) 240px;
    align-items: end;
  }

  .page-about .about-hero-meta {
    flex-direction: column;
    gap: 18px;
    padding-top: 0;
    padding-left: 24px;
    border-top: none;
    border-left: 1px solid var(--about-line);
  }

  .page-about .about-origin-grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 7fr);
    align-items: start;
  }

  .page-about .about-method-grid {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 0.85fr);
    gap: clamp(32px, 4vw, 56px);
    align-items: start;
  }

  .page-about .about-method-head {
    grid-column: 1 / -1;
  }

  .page-about .method-list {
    grid-column: 1;
  }

  .page-about .about-method-figure {
    grid-column: 2;
  }

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

  .page-about .team-stats {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .stage-board,
  .page-about .stage-year-note,
  .page-about .about-next a {
    transition: none;
  }

  .page-about .stage-row:hover .stage-board,
  .page-about .stage-row:focus-within .stage-board {
    transform: none;
  }
}