.page-about {
  --about-brick: #E08063;
  --about-hair: 1px solid var(--line);
  background: var(--ink);
  color: var(--paper);
  padding-top: clamp(8px, 2vw, 18px);
  padding-bottom: clamp(40px, 8vw, 88px);
}

.page-about a:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: clamp(20px, 4vw, 40px) 0 clamp(26px, 4vw, 44px);
  border-bottom: var(--about-hair);
}

.page-about .about-hero h1 {
  margin: 16px 0 0;
  max-width: 20em;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(30px, 5.6vw, 58px);
  line-height: 1.16;
  letter-spacing: -.02em;
  color: var(--paper);
}

.page-about .about-hero .lede {
  margin: 22px 0 0;
  max-width: 62ch;
  font-size: clamp(15px, 1.35vw, 17px);
  line-height: 1.9;
  color: var(--muted);
}

.page-about .hero-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 30px;
  margin: 30px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .hero-facts li {
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding-left: 12px;
  border-left: var(--about-hair);
  font-size: 13px;
  color: var(--muted);
}

.page-about .hero-facts .u-mono {
  color: var(--gold);
  font-size: 15px;
  letter-spacing: .04em;
}

/* ---------- 非对称双栏骨架 ---------- */
.page-about .about-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 30px;
  padding-top: clamp(24px, 4vw, 46px);
}

.page-about .about-index .index-title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--gold);
}

.page-about .about-index ol {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 18px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-index a {
  display: block;
  padding: 6px 0 6px 14px;
  border-left: 2px solid transparent;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .02em;
  color: var(--muted);
  text-decoration: none;
  transition: color .18s var(--ease), border-color .18s var(--ease);
}

.page-about .about-index a:hover {
  color: var(--gold-soft);
}

.page-about .about-index a[aria-current="true"] {
  color: var(--gold);
  border-left-color: var(--gold);
}

@media (min-width: 900px) {
  .page-about .about-grid {
    grid-template-columns: 176px minmax(0, 1fr);
    gap: clamp(30px, 4vw, 56px);
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--header-h) + 30px);
    align-self: start;
  }

  .page-about .about-index ol {
    flex-direction: column;
    gap: 2px;
  }
}

/* ---------- 区块头部 ---------- */
.page-about .about-sec {
  padding: clamp(34px, 5.5vw, 68px) 0;
}

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

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

.page-about .sec-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 18px;
}

.page-about .sec-num {
  padding: 3px 10px;
  border: var(--about-hair);
  border-radius: 999px;
  color: var(--gold);
  font-size: 12px;
  letter-spacing: .1em;
}

.page-about .sec-head h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(21px, 2.9vw, 33px);
  line-height: 1.25;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .sec-lede {
  margin: 0 0 26px;
  max-width: 60ch;
  font-size: 14.5px;
  line-height: 1.9;
  color: var(--muted);
}

/* ---------- 01 品牌档案 ---------- */
.page-about .archive-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.page-about .archive-copy p {
  margin: 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--muted);
}

.page-about .archive-copy p + p {
  margin-top: 14px;
}

.page-about .archive-copy a,
.page-about .versions-foot a,
.page-about .timeline a,
.page-about .contact-note a {
  color: var(--gold-soft);
  text-decoration: none;
  border-bottom: 1px solid rgba(240, 206, 134, .38);
}

.page-about .archive-copy a:hover,
.page-about .versions-foot a:hover,
.page-about .timeline a:hover,
.page-about .contact-note a:hover {
  color: var(--gold);
}

.page-about .archive-figure {
  aspect-ratio: 5 / 2;
  margin: 0;
  opacity: .92;
}

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

@media (min-width: 820px) {
  .page-about .archive-layout {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.08fr);
    align-items: start;
    gap: 36px;
  }
}

.page-about .year-line {
  margin: 30px 0 0;
  padding: 0;
  list-style: none;
  border-top: var(--about-hair);
}

.page-about .year-line li {
  display: grid;
  grid-template-columns: 96px minmax(0, 1fr);
  gap: 16px;
  padding: 14px 0;
  border-bottom: var(--about-hair);
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .year-line .u-mono {
  color: var(--gold-soft);
  font-size: 12.5px;
  letter-spacing: .05em;
}

/* ---------- 02 改动清单 ---------- */
.page-about .change-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

.page-about .change-list {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: var(--about-hair);
}

.page-about .change-item {
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 14px;
  padding: 18px 12px 18px 10px;
  border-bottom: var(--about-hair);
  transition: background .2s var(--ease);
}

.page-about .change-item:hover {
  background: rgba(217, 164, 65, .055);
}

.page-about .change-id {
  padding-top: 4px;
  color: var(--gold);
  font-size: 12.5px;
  letter-spacing: .06em;
}

.page-about .change-body h3 {
  margin: 0 0 6px;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 16.5px;
  letter-spacing: .01em;
  color: var(--paper);
}

.page-about .change-body > p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .change-delta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 10px;
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .01em;
}

.page-about .delta-before {
  color: var(--muted);
  opacity: .7;
  text-decoration: line-through;
  text-decoration-color: rgba(232, 128, 99, .8);
}

.page-about .delta-arrow {
  color: var(--gold);
}

.page-about .delta-after {
  color: var(--gold-soft);
}

.page-about .change-figure {
  aspect-ratio: 3 / 4;
  margin: 0;
}

@media (min-width: 880px) {
  .page-about .change-layout {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, .72fr);
    align-items: start;
    gap: 40px;
  }
}

/* ---------- 03 机型分级 ---------- */
.page-about .tier-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .tier-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 24px 20px 24px;
  border: var(--about-hair);
  border-radius: var(--radius-m);
  background: linear-gradient(180deg, var(--ink-2) 0%, rgba(23, 58, 49, .5) 100%);
}

.page-about .tier-tag {
  align-self: flex-start;
  padding: 3px 11px;
  border-radius: 999px;
  background: var(--gold);
  color: var(--ink);
  font-size: 11px;
  letter-spacing: .14em;
}

.page-about .tier-card h3 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 22px;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .tier-card > p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .tier-list {
  display: grid;
  gap: 9px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .tier-list li {
  position: relative;
  padding-left: 17px;
  font-size: 13.5px;
  line-height: 1.72;
  color: var(--paper);
  opacity: .88;
}

.page-about .tier-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--gold);
}

.page-about .tier-note {
  margin-top: auto !important;
  padding-top: 12px;
  border-top: 1px dashed rgba(232, 128, 99, .45);
  color: var(--about-brick) !important;
  font-size: 12.5px;
  line-height: 1.75;
}

.page-about .tier-figure {
  aspect-ratio: 4 / 3;
  margin: 6px 0 0;
}

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

  .page-about .tier-card:nth-child(2) {
    transform: translateY(22px);
  }

  .page-about .tier-card:nth-child(3) {
    transform: translateY(44px);
  }

  .page-about #devices {
    padding-bottom: clamp(70px, 8vw, 110px);
  }
}

/* ---------- 04 旧版查阅 ---------- */
.page-about .version-rows {
  display: grid;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .version-row {
  position: relative;
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  padding: 16px 18px 16px 22px;
  border: var(--about-hair);
  border-radius: var(--radius-s);
  background: rgba(23, 58, 49, .48);
  overflow: hidden;
}

.page-about .version-row::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--gold);
  transform: scaleY(.2);
  transform-origin: top;
  transition: transform .55s var(--ease);
}

.page-about .version-row:hover::before,
.page-about .version-row.is-in::before {
  transform: scaleY(1);
}

.page-about .version-row:hover {
  border-color: var(--gold-soft);
}

.page-about .version-field {
  color: var(--gold);
  font-size: 12.5px;
  letter-spacing: .08em;
}

.page-about .version-text {
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--muted);
}

@media (min-width: 700px) {
  .page-about .version-row {
    grid-template-columns: 124px minmax(0, 1fr);
    align-items: baseline;
    gap: 20px;
    padding: 18px 22px 18px 24px;
  }
}

.page-about .versions-foot {
  margin: 22px 0 0;
  font-size: 14px;
  line-height: 1.85;
  color: var(--muted);
}

/* ---------- 05 更新节奏 ---------- */
.page-about .timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 28px;
  list-style: none;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--gold) 0%, var(--line) 60%, transparent 100%);
}

.page-about .timeline li {
  position: relative;
  padding-bottom: 24px;
}

.page-about .timeline li:last-child {
  padding-bottom: 0;
}

.page-about .timeline li::before {
  content: "";
  position: absolute;
  left: -28px;
  top: 5px;
  width: 11px;
  height: 11px;
  border: 2px solid var(--gold);
  border-radius: 50%;
  background: var(--ink);
}

.page-about .timeline h3 {
  margin: 0 0 6px;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 16px;
  letter-spacing: .01em;
  color: var(--paper);
}

.page-about .timeline p {
  margin: 0;
  max-width: 58ch;
  font-size: 14px;
  line-height: 1.85;
  color: var(--muted);
}

.page-about .contact-note {
  display: grid;
  gap: 16px;
  margin-top: 34px;
  padding: clamp(20px, 3vw, 28px);
}

.page-about .contact-note p {
  margin: 0;
  max-width: 68ch;
  font-size: 14.5px;
  line-height: 1.9;
  color: var(--muted);
}

.page-about .contact-note .btn {
  justify-self: start;
  margin: 0;
}

@media (min-width: 1100px) {
  .page-about .change-list {
    padding-right: 8px;
  }
}
</main>