.page-about {
  --about-line: var(--grid);
  --about-tint: rgba(216, 32, 42, 0.07);
  position: relative;
  background-color: var(--paper);
  background-image: repeating-linear-gradient(
    to right,
    rgba(217, 210, 195, 0.45) 0,
    rgba(217, 210, 195, 0.45) 1px,
    transparent 1px,
    transparent 4.5rem
  );
  color: var(--ink);
  font-family: var(--font-body);
  overflow-x: hidden;
}

.page-about .container {
  width: 100%;
  max-width: var(--content-max);
  margin: 0 auto;
  padding: 0 1.15rem;
}

.page-about .breadcrumb {
  padding: 1.1rem 0 0.4rem;
}

.page-about .breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.page-about .breadcrumb__item + .breadcrumb__item::before {
  content: "/";
  margin-right: 0.35rem;
  color: var(--grid);
}

.page-about .breadcrumb__link {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}

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

/* ---------- 首屏拼贴 ---------- */
.page-about .about-hero {
  display: grid;
  gap: 1.6rem;
  padding: 1.2rem 0 2.4rem;
  border-bottom: 1px solid var(--about-line);
}

.page-about .kicker {
  display: inline-block;
  margin: 0 0 0.9rem;
  padding: 0.28rem 0.6rem;
  background: var(--ink);
  color: var(--glove);
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
}

.page-about .about-hero__title {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: clamp(1.85rem, 6.2vw, 3.4rem);
  line-height: 1.08;
  letter-spacing: -0.015em;
  color: var(--ink);
  max-width: 22ch;
}

.page-about .about-hero__title::after {
  content: "";
  display: block;
  width: 4.5rem;
  height: 0.42rem;
  margin-top: 1.05rem;
  background: var(--red);
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: 34rem;
  font-size: 0.97rem;
  line-height: 1.85;
  color: var(--ink);
}

.page-about .about-hero__jump {
  display: grid;
  gap: 0.5rem;
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
}

.page-about .about-hero__jump li {
  min-width: 0;
}

.page-about .about-hero__jump a {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.55rem 0.75rem;
  border: 1px solid var(--ink);
  background: var(--glove);
  color: var(--ink);
  font-size: 0.84rem;
  line-height: 1.4;
  text-decoration: none;
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out), transform 0.2s var(--ease-out);
}

.page-about .about-hero__jump-num {
  flex: none;
  font-family: var(--font-display);
  font-size: 0.76rem;
  padding: 0.1rem 0.34rem;
  background: var(--red);
  color: var(--glove);
}

.page-about .about-hero__jump a:hover,
.page-about .about-hero__jump a:focus-visible {
  background: var(--ink);
  color: var(--glove);
  transform: translateX(3px);
}

.page-about .about-hero__jump a:hover .about-hero__jump-num,
.page-about .about-hero__jump a:focus-visible .about-hero__jump-num {
  background: var(--yellow);
  color: var(--ink);
}

.page-about .about-hero__media {
  position: relative;
  margin: 0;
  border: 1px solid var(--ink);
  background: var(--glove);
}

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

.page-about .about-hero__tag {
  position: absolute;
  left: 0;
  bottom: 0;
  padding: 0.35rem 0.7rem;
  background: var(--yellow);
  color: var(--ink);
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
}

/* ---------- 章节骨架 ---------- */
.page-about .chapter {
  padding: 2.4rem 0;
  border-bottom: 1px solid var(--about-line);
}

.page-about .chapter__head {
  display: flex;
  align-items: flex-start;
  gap: 0.85rem;
  margin-bottom: 1.3rem;
}

.page-about .chapter__num {
  flex: none;
  font-family: var(--font-display);
  font-size: clamp(2rem, 7vw, 3.4rem);
  line-height: 0.82;
  color: var(--red);
}

.page-about .chapter__title {
  margin: 0;
  padding-top: 0.1rem;
  font-family: var(--font-display);
  font-size: clamp(1.3rem, 4.4vw, 2rem);
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .chapter__body {
  display: grid;
  gap: 1.4rem;
  min-width: 0;
}

.page-about .chapter__lede {
  margin: 0 0 1.2rem;
  font-size: 0.95rem;
  line-height: 1.85;
  color: var(--ink);
  border-left: 4px solid var(--yellow);
  padding-left: 0.9rem;
}

.page-about .prose p {
  margin: 0 0 1rem;
  font-size: 0.94rem;
  line-height: 1.9;
  color: var(--ink);
  max-width: 38rem;
}

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

.page-about .prose a {
  color: var(--red);
  text-decoration: none;
  border-bottom: 1px solid var(--red);
}

.page-about .prose a:hover,
.page-about .prose a:focus-visible {
  background: var(--about-tint);
}

/* ---------- 边注 ---------- */
.page-about .note {
  align-self: start;
  border-left: 4px solid var(--yellow);
  background: var(--glove);
  padding: 0.15rem 0.9rem;
}

.page-about .note__summary {
  cursor: pointer;
  padding: 0.75rem 0;
  font-family: var(--font-display);
  font-size: 0.9rem;
  line-height: 1.45;
  color: var(--ink);
  list-style: none;
}

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

.page-about .note__summary::before {
  content: "＋";
  display: inline-block;
  margin-right: 0.45rem;
  color: var(--red);
  font-family: var(--font-display);
}

.page-about .note__details[open] .note__summary::before {
  content: "－";
}

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

.page-about .note__body {
  padding-bottom: 0.8rem;
  border-top: 1px solid var(--about-line);
  margin-top: 0.1rem;
}

.page-about .note__body p {
  margin: 0.7rem 0 0;
  font-size: 0.86rem;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .note__body a {
  color: var(--red);
  text-decoration: none;
  border-bottom: 1px solid var(--red);
}

/* ---------- 章节分栏 ---------- */
.page-about .chapter__body--split > * {
  min-width: 0;
}

/* ---------- 设计原则阶梯 ---------- */
.page-about .principle-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.7rem;
}

.page-about .principle {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.35rem 0.8rem;
  padding: 0.85rem 0.9rem;
  background: var(--glove);
  border-top: 3px solid var(--red);
  transition: transform 0.2s var(--ease-out), box-shadow 0.2s var(--ease-out);
}

.page-about .principle--yellow {
  border-top-color: var(--yellow);
}

.page-about .principle--blue {
  border-top-color: var(--blue);
}

.page-about .principle--ink {
  border-top-color: var(--ink);
}

.page-about .principle__num {
  grid-row: span 2;
  font-family: var(--font-display);
  font-size: 0.72rem;
  line-height: 1.6;
  padding: 0.1rem 0.36rem;
  height: fit-content;
  background: var(--ink);
  color: var(--glove);
}

.page-about .principle__title {
  margin: 0;
  font-family: var(--font-display);
  font-size: 0.98rem;
  line-height: 1.4;
  color: var(--ink);
}

.page-about .principle__text {
  grid-column: 2;
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .principle:hover {
  transform: translateX(3px);
  box-shadow: -3px 0 0 var(--red);
}

/* ---------- 配图 ---------- */
.page-about .about-figure {
  margin: 0;
  border: 1px solid var(--ink);
  background: var(--glove);
}

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

.page-about .about-figure__caption {
  padding: 0.6rem 0.8rem;
  border-top: 1px solid var(--about-line);
  font-size: 0.78rem;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- 时间线 ---------- */
.page-about .timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 0.2rem;
}

.page-about .timeline__item {
  position: relative;
  padding: 0.2rem 0 1.35rem 1.7rem;
  border-left: 2px solid var(--grid);
}

.page-about .timeline__item:last-child {
  padding-bottom: 0.2rem;
}

.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -0.44rem;
  top: 0.5rem;
  width: 0.75rem;
  height: 0.75rem;
  background: var(--red);
  transition: transform 0.2s var(--ease-out), background 0.2s var(--ease-out);
}

.page-about .timeline__item:nth-child(2)::before {
  background: var(--yellow);
}

.page-about .timeline__item:nth-child(3)::before {
  background: var(--blue);
}

.page-about .timeline__item:nth-child(4)::before {
  background: var(--ink);
}

.page-about .timeline__item:hover::before {
  transform: scale(1.25);
}

.page-about .timeline__when {
  display: inline-block;
  margin-bottom: 0.3rem;
  padding: 0.1rem 0.45rem;
  background: var(--ink);
  color: var(--glove);
  font-family: var(--font-display);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
}

.page-about .timeline__label {
  margin: 0 0 0.3rem;
  font-family: var(--font-display);
  font-size: 0.96rem;
  line-height: 1.4;
  color: var(--ink);
}

.page-about .timeline__text {
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .timeline__text a {
  color: var(--red);
  text-decoration: none;
  border-bottom: 1px solid var(--red);
}

/* ---------- 联系块 ---------- */
.page-about .about-contact {
  background: var(--ink);
  color: var(--glove);
  padding: 1.15rem 1.1rem 1.25rem;
  border-left: 6px solid var(--red);
}

.page-about .about-contact__head {
  margin: 0 0 0.9rem;
  font-family: var(--font-display);
  font-size: 0.78rem;
  letter-spacing: 0.18em;
  color: var(--yellow);
}

.page-about .about-contact__list {
  margin: 0;
  display: grid;
  gap: 0.65rem;
}

.page-about .about-contact__row {
  display: grid;
  gap: 0.15rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.16);
}

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

.page-about .about-contact__row dt {
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  color: rgba(255, 255, 255, 0.62);
}

.page-about .about-contact__row dd {
  margin: 0;
  font-size: 0.92rem;
  line-height: 1.55;
  word-break: break-word;
}

.page-about .about-contact__row a {
  color: var(--glove);
  text-decoration: none;
  border-bottom: 1px solid var(--yellow);
}

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

.page-about .about-contact__note {
  margin: 0.95rem 0 0;
  font-size: 0.78rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.68);
}

.page-about .about-contact__note a {
  color: var(--yellow);
  text-decoration: none;
  border-bottom: 1px solid var(--yellow);
}

/* ---------- 收尾 CTA ---------- */
.page-about .chapter--closing {
  border-bottom: 0;
  padding-bottom: 3rem;
}

.page-about .about-cta {
  background: var(--red);
  color: var(--glove);
  padding: 1.5rem 1.2rem 1.6rem;
  border: 1px solid var(--red-deep);
}

.page-about .about-cta__text {
  margin: 0 0 1.1rem;
  max-width: 40rem;
  font-size: 0.95rem;
  line-height: 1.85;
  color: var(--glove);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.page-about .about-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.65rem 1.05rem;
  font-family: var(--font-display);
  font-size: 0.85rem;
  letter-spacing: 0.04em;
  text-decoration: none;
  border: 2px solid var(--glove);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
}

.page-about .about-btn--solid {
  background: var(--glove);
  color: var(--red-deep);
}

.page-about .about-btn--line {
  background: transparent;
  color: var(--glove);
}

.page-about .about-btn--solid:hover,
.page-about .about-btn--solid:focus-visible {
  background: var(--yellow);
  border-color: var(--yellow);
  color: var(--ink);
}

.page-about .about-btn--line:hover,
.page-about .about-btn--line:focus-visible {
  background: var(--glove);
  color: var(--red-deep);
}

.page-about .about-btn__arrow {
  display: inline-block;
  transition: transform 0.2s var(--ease-out);
}

.page-about .about-btn:hover .about-btn__arrow,
.page-about .about-btn:focus-visible .about-btn__arrow {
  transform: translateX(3px);
}

.page-about .about-btn:focus-visible,
.page-about .about-hero__jump a:focus-visible,
.page-about .breadcrumb__link:focus-visible,
.page-about .about-backlink:focus-visible {
  outline: 3px solid var(--blue);
  outline-offset: 2px;
}

/* ---------- 回索引浮标 ---------- */
.page-about .about-backlink {
  position: fixed;
  right: 0.9rem;
  bottom: 0.9rem;
  z-index: 20;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.55rem 0.85rem;
  background: var(--ink);
  color: var(--glove);
  font-family: var(--font-display);
  font-size: 0.76rem;
  letter-spacing: 0.06em;
  text-decoration: none;
  border: 1px solid var(--ink);
  box-shadow: 0 8px 20px rgba(23, 24, 28, 0.22);
}

.page-about .about-backlink:hover,
.page-about .about-backlink:focus-visible {
  background: var(--red);
  border-color: var(--red);
}

/* ---------- 平板 ---------- */
@media (min-width: 44rem) {
  .page-about .container {
    padding: 0 1.75rem;
  }

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

  .page-about .about-hero__media img,
  .page-about .about-figure img {
    max-height: 30rem;
  }

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

  .page-about .about-contact__row {
    grid-template-columns: 6.5rem minmax(0, 1fr);
    align-items: baseline;
    gap: 0.6rem;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 62rem) {
  .page-about .container {
    padding: 0 2.5rem;
  }

  .page-about .about-hero {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
    align-items: end;
    gap: 2.2rem;
    padding: 1.6rem 0 3rem;
  }

  .page-about .about-hero__jump {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    max-width: 32rem;
  }

  .page-about .chapter {
    padding: 3.2rem 0;
  }

  .page-about .chapter__head {
    gap: 1.4rem;
    margin-bottom: 1.6rem;
  }

  .page-about .chapter__num {
    font-size: 3.6rem;
  }

  .page-about .chapter__body {
    grid-template-columns: minmax(0, 1.55fr) minmax(0, 0.85fr);
    gap: 2.2rem;
    align-items: start;
  }

  .page-about .chapter__body--split {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
    gap: 2.4rem;
  }

  .page-about .principle-list {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.8rem;
  }

  .page-about .principle:nth-child(2) {
    margin-left: 1.3rem;
  }

  .page-about .principle:nth-child(3) {
    margin-left: 2.6rem;
  }

  .page-about .principle:nth-child(4) {
    margin-left: 3.9rem;
  }

  .page-about .about-figure--sticky {
    position: sticky;
    top: 2rem;
  }

  .page-about .about-cta {
    padding: 2rem 2rem 2.1rem;
  }

  .page-about .about-cta__text {
    font-size: 1rem;
  }

  .page-about .about-backlink {
    right: 1.6rem;
    bottom: 1.6rem;
  }
}

@media (min-width: 80rem) {
  .page-about .chapter__title {
    font-size: 2.1rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-hero__jump a,
  .page-about .principle,
  .page-about .timeline__item::before,
  .page-about .about-btn,
  .page-about .about-btn__arrow {
    transition: none;
  }

  .page-about .about-hero__jump a:hover,
  .page-about .principle:hover {
    transform: none;
  }
}