.page-about {
  --about-hair: rgba(42, 53, 99, 0.78);
  --about-gold-line: rgba(232, 176, 75, 0.72);
  --about-soft: rgba(11, 18, 48, 0.74);
  position: relative;
  color: var(--paper);
  background:
    radial-gradient(140% 55% at 88% -8%, rgba(53, 230, 208, 0.1), transparent 58%),
    linear-gradient(180deg, var(--ink-900) 0%, var(--ink-800) 48%, var(--panel) 100%);
  overflow-x: clip;
}

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

/* ============ 首屏 ============ */
.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding: clamp(1.3rem, 4vw, 2.2rem) 0 clamp(2.6rem, 6vw, 4.6rem);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: 0.55;
  background-image:
    repeating-linear-gradient(0deg, rgba(42, 53, 99, 0.34) 0 1px, transparent 1px 48px),
    repeating-linear-gradient(90deg, rgba(42, 53, 99, 0.26) 0 1px, transparent 1px 48px);
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 84%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 84%);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  right: -8%;
  top: 10%;
  width: 48%;
  height: 64%;
  z-index: -1;
  pointer-events: none;
  transform: skewY(-8deg);
  background: linear-gradient(135deg, rgba(255, 61, 138, 0.14), rgba(53, 230, 208, 0.07) 58%, transparent 86%);
}

.page-about .about-hero__grid {
  display: grid;
  gap: 2rem;
  margin-top: clamp(1.4rem, 3.5vw, 2.2rem);
}

.page-about .about-hero__title {
  margin: 0.7rem 0 0;
  font-family: var(--font-sans);
  font-weight: 900;
  font-size: clamp(2.15rem, 7.6vw, 4.4rem);
  line-height: 1.04;
  letter-spacing: -0.02em;
  margin-left: -0.04em;
  text-wrap: balance;
}

.page-about .about-hero__title-em {
  color: var(--cyan);
  background: linear-gradient(92deg, var(--cyan), #7ef3e2 60%, var(--gold));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.page-about .about-hero__lede {
  margin: 1.1rem 0 0;
  max-width: 34rem;
  font-size: 1.02rem;
  line-height: 1.78;
  color: var(--paper-dim);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem 1.4rem;
  align-items: center;
  margin-top: 1.7rem;
}

.page-about .about-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.82rem 1.5rem;
  border: 1px solid var(--cyan);
  border-radius: var(--radius);
  background: var(--cyan);
  color: var(--ink-900);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  text-decoration: none;
  transition: background 0.22s var(--ease), color 0.22s var(--ease), transform 0.22s var(--ease);
}

.page-about .about-btn:hover,
.page-about .about-btn:focus-visible {
  background: transparent;
  color: var(--cyan);
  transform: translateY(-1px);
}

.page-about .about-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--paper);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  padding-bottom: 0.2rem;
  border-bottom: 1px solid var(--about-gold-line);
  transition: color 0.22s var(--ease), border-color 0.22s var(--ease);
}

.page-about .about-link:hover,
.page-about .about-link:focus-visible {
  color: var(--gold);
  border-color: var(--gold);
}

.page-about .about-hero__panel {
  padding: 1.2rem 1.1rem 1.1rem;
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--about-hair);
  box-shadow: var(--shadow-panel);
  clip-path: polygon(0 20px, 100% 0, 100% 100%, 0 100%);
}

.page-about .about-hero__panel-title {
  margin: 0 0 0.9rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.22em;
  color: var(--gold);
  text-transform: uppercase;
}

.page-about .about-hero__stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.85rem 1rem;
}

.page-about .about-hero__stat {
  display: grid;
  gap: 0.15rem;
  padding-top: 0.6rem;
  border-top: 1px dashed var(--about-hair);
}

.page-about .about-hero__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.45rem, 4vw, 1.9rem);
  font-weight: 700;
  color: var(--cyan);
  line-height: 1.05;
}

.page-about .about-hero__lbl {
  font-size: 0.78rem;
  line-height: 1.5;
  color: var(--mist);
}

.page-about .about-hero__panel-foot {
  margin: 1rem 0 0;
  padding-top: 0.8rem;
  border-top: 1px solid var(--about-hair);
  font-size: 0.78rem;
  line-height: 1.7;
  color: var(--mist);
}

/* ============ 章节通用 ============ */
.page-about .about-sec {
  position: relative;
  padding: clamp(2.6rem, 6vw, 4.6rem) 0;
}

.page-about .sec-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.6rem 1rem;
  align-items: start;
  margin-bottom: clamp(1.6rem, 4vw, 2.6rem);
}

.page-about .sec-head__index {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(2.4rem, 7vw, 4.2rem);
  font-weight: 700;
  line-height: 0.82;
  color: var(--gold);
  opacity: 0.4;
}

.page-about .sec-head__body {
  min-width: 0;
}

.page-about .sec-head__title {
  margin: 0.35rem 0 0;
  font-family: var(--font-sans);
  font-weight: 900;
  font-size: clamp(1.55rem, 4.4vw, 2.45rem);
  line-height: 1.18;
  letter-spacing: -0.02em;
  color: var(--paper);
}

.page-about .sec-head__lede {
  margin: 0.7rem 0 0;
  max-width: 40rem;
  font-size: 0.98rem;
  line-height: 1.8;
  color: var(--paper-dim);
}

.page-about .sec-head--light .sec-head__title {
  color: var(--ink-900);
}

.page-about .sec-head--light .sec-head__lede {
  color: var(--about-soft);
}

.page-about .sec-head--light .sec-head__index {
  color: var(--ink-900);
  opacity: 0.16;
}

.page-about .sec-head--light .eyebrow {
  color: var(--cinnabar);
}

/* ============ 01 时间线 ============ */
.page-about .about-sec--origin {
  background:
    linear-gradient(180deg, transparent, rgba(32, 44, 96, 0.18) 55%, transparent);
}

.page-about .tl {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0.4rem 0 0 1.9rem;
}

.page-about .tl::before {
  content: "";
  position: absolute;
  left: 0.44rem;
  top: 0.5rem;
  width: 1px;
  height: calc(100% + 1rem);
  background: linear-gradient(180deg, rgba(232, 176, 75, 0) 0%, var(--about-gold-line) 9%, rgba(232, 176, 75, 0.5) 74%, rgba(232, 176, 75, 0) 100%);
  transform: rotate(2.6deg);
  transform-origin: top left;
}

.page-about .tl__item {
  position: relative;
  padding: 0 0 clamp(1.6rem, 4vw, 2.3rem);
}

.page-about .tl__item::before {
  content: "";
  position: absolute;
  left: -1.53rem;
  top: 0.62rem;
  width: 0.58rem;
  height: 0.58rem;
  background: var(--ink-900);
  border: 1px solid var(--gold);
  transform: rotate(45deg);
}

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

.page-about .tl__tag {
  display: inline-block;
  margin-bottom: 0.3rem;
  padding: 0.1rem 0.42rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  color: var(--ink-900);
  background: var(--gold);
  border-radius: var(--radius);
}

.page-about .tl__stage {
  margin: 0.35rem 0 0;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.1em;
  color: var(--mist);
}

.page-about .tl__title {
  margin: 0.35rem 0 0;
  font-size: clamp(1.12rem, 3vw, 1.35rem);
  font-weight: 800;
  line-height: 1.4;
  color: var(--paper);
}

.page-about .tl__text {
  margin: 0.5rem 0 0;
  max-width: 42rem;
  font-size: 0.94rem;
  line-height: 1.8;
  color: var(--paper-dim);
}

.page-about .tl__more {
  margin-top: 0.75rem;
  max-width: 40rem;
  border-left: 2px solid var(--about-gold-line);
  padding-left: 0.8rem;
}

.page-about .tl__more summary {
  cursor: pointer;
  list-style: none;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--gold);
  padding: 0.15rem 0;
}

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

.page-about .tl__more summary::before {
  content: "＋";
  margin-right: 0.4rem;
  font-family: var(--font-mono);
}

.page-about .tl__more[open] summary::before {
  content: "－";
}

.page-about .tl__more p {
  margin: 0.5rem 0 0;
  font-size: 0.88rem;
  line-height: 1.75;
  color: var(--mist);
}

/* ============ 02 流水线 ============ */
.page-about .about-sec--pipeline {
  background: linear-gradient(180deg, transparent, rgba(20, 28, 66, 0.72) 40%, transparent);
}

.page-about .pipe {
  display: grid;
  gap: 1.4rem;
}

.page-about .flow {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.8rem;
}

.page-about .flow__step {
  min-width: 0;
}

.page-about .flow__detail {
  height: 100%;
  background: linear-gradient(180deg, rgba(26, 36, 80, 0.9), rgba(20, 28, 66, 0.9));
  border: 1px solid var(--about-hair);
  border-radius: var(--radius);
  transition: border-color 0.22s var(--ease), box-shadow 0.22s var(--ease);
}

.page-about .flow__detail[open] {
  border-color: rgba(53, 230, 208, 0.55);
  box-shadow: var(--shadow-panel);
}

.page-about .flow__sum {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.15rem 0.7rem;
  padding: 0.9rem 0.95rem;
  cursor: pointer;
  list-style: none;
  align-items: baseline;
}

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

.page-about .flow__num {
  grid-row: 1 / span 2;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--gold);
  line-height: 1.1;
  align-self: center;
}

.page-about .flow__name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .flow__time {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

.page-about .flow__panel {
  padding: 0.2rem 0.95rem 0.95rem 2.8rem;
  border-top: 1px dashed var(--about-hair);
  margin-top: 0.15rem;
}

.page-about .flow__panel p {
  margin: 0.6rem 0 0;
  font-size: 0.88rem;
  line-height: 1.78;
  color: var(--paper-dim);
}

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

.page-about .pipe__caption {
  margin-top: 0.65rem;
  font-size: 0.78rem;
  line-height: 1.7;
  color: var(--mist);
  border-left: 2px solid var(--cyan);
  padding-left: 0.65rem;
}

/* ============ 03 团队 ============ */
.page-about .crew {
  display: grid;
  gap: 1.3rem;
}

.page-about .crew__card {
  padding-top: 0.9rem;
  border-top: 2px solid var(--cyan);
}

.page-about .crew__card:nth-child(2) {
  border-top-color: var(--gold);
}

.page-about .crew__card:nth-child(3) {
  border-top-color: var(--magenta);
}

.page-about .crew__count {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(2rem, 5vw, 2.6rem);
  font-weight: 700;
  line-height: 1;
  color: var(--paper);
}

.page-about .crew__name {
  margin: 0.5rem 0 0;
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--cyan);
}

.page-about .crew__card:nth-child(2) .crew__name {
  color: var(--gold);
}

.page-about .crew__card:nth-child(3) .crew__name {
  color: var(--magenta);
}

.page-about .crew__text {
  margin: 0.55rem 0 0;
  font-size: 0.92rem;
  line-height: 1.8;
  color: var(--paper-dim);
}

.page-about .crew__note {
  margin: clamp(1.4rem, 3.5vw, 2rem) 0 0;
  padding: 0.9rem 1rem;
  font-size: 0.88rem;
  line-height: 1.8;
  color: var(--paper-dim);
  background: rgba(20, 28, 66, 0.6);
  border-left: 2px solid var(--gold);
}

.page-about .crew__note a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 230, 208, 0.45);
}

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

/* ============ 04 版本治理 ============ */
.page-about .about-sec--versions {
  position: relative;
  isolation: isolate;
  overflow: clip;
}

.page-about .versions__bg {
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
}

.page-about .versions__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.26;
  filter: saturate(0.85) brightness(0.9);
}

.page-about .about-sec--versions::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background: linear-gradient(180deg, rgba(11, 18, 48, 0.86) 0%, rgba(20, 28, 66, 0.72) 55%, rgba(26, 36, 80, 0.9) 100%);
}

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

.page-about .versions__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1rem;
}

.page-about .versions__item {
  padding: 1rem 1rem 1.05rem;
  background: rgba(11, 18, 48, 0.62);
  border: 1px solid var(--about-hair);
  border-left: 2px solid var(--gold);
  backdrop-filter: blur(2px);
}

.page-about .versions__name {
  margin: 0;
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--gold);
}

.page-about .versions__item p {
  margin: 0.5rem 0 0;
  font-size: 0.9rem;
  line-height: 1.8;
  color: var(--paper-dim);
}

.page-about .versions__item a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 230, 208, 0.45);
}

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

/* ============ 05 合作（暖纸收束） ============ */
.page-about .about-coop {
  position: relative;
  margin-top: clamp(1rem, 3vw, 2rem);
  padding: 3.6rem 0 clamp(2.4rem, 6vw, 3.6rem);
  background: var(--paper);
  color: var(--ink-900);
  clip-path: polygon(0 40px, 100% 0, 100% 100%, 0 100%);
}

.page-about .coop__banner {
  margin: 0 0 clamp(1.6rem, 4vw, 2.4rem);
  overflow: hidden;
  clip-path: polygon(0 0, 100% 0, 100% 88%, 0 100%);
  background: var(--ink-800);
}

.page-about .coop__banner-img {
  width: 100%;
  height: clamp(150px, 30vw, 260px);
  object-fit: cover;
}

.page-about .coop__grid {
  display: grid;
  gap: 1.1rem;
  margin-top: clamp(0.6rem, 2vw, 1rem);
}

.page-about .coop__card {
  padding: 1rem 0 0;
  border-top: 2px solid var(--cinnabar);
}

.page-about .coop__name {
  margin: 0;
  font-size: 1.02rem;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--ink-900);
}

.page-about .coop__text {
  margin: 0.5rem 0 0;
  font-size: 0.92rem;
  line-height: 1.8;
  color: var(--about-soft);
}

.page-about .coop__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.85rem 1.5rem;
  margin-top: clamp(1.5rem, 4vw, 2.2rem);
  padding-top: clamp(1rem, 3vw, 1.5rem);
  border-top: 1px solid rgba(11, 18, 48, 0.16);
}

.page-about .coop__btn {
  display: inline-flex;
  align-items: center;
  padding: 0.82rem 1.5rem;
  background: var(--ink-900);
  color: var(--paper);
  border: 1px solid var(--ink-900);
  border-radius: var(--radius);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  text-decoration: none;
  transition: background 0.22s var(--ease), border-color 0.22s var(--ease), transform 0.22s var(--ease);
}

.page-about .coop__btn:hover,
.page-about .coop__btn:focus-visible {
  background: var(--cinnabar);
  border-color: var(--cinnabar);
  transform: translateY(-1px);
}

.page-about .coop__link {
  color: var(--ink-900);
  font-weight: 600;
  font-size: 0.92rem;
  text-decoration: none;
  padding-bottom: 0.18rem;
  border-bottom: 1px solid rgba(11, 18, 48, 0.35);
  transition: color 0.22s var(--ease), border-color 0.22s var(--ease);
}

.page-about .coop__link:hover,
.page-about .coop__link:focus-visible {
  color: var(--cinnabar);
  border-color: var(--cinnabar);
}

/* ============ 响应式 ============ */
@media (min-width: 640px) {
  .page-about .flow {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .crew {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.1rem;
  }

  .page-about .coop__grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.4rem;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1fr) 330px;
    gap: clamp(2rem, 4vw, 3.2rem);
    align-items: end;
  }

  .page-about .about-hero__panel {
    align-self: start;
    margin-top: 2.4rem;
  }

  .page-about .pipe {
    grid-template-columns: minmax(0, 1.45fr) minmax(0, 0.55fr);
    gap: 1.8rem;
    align-items: start;
  }

  .page-about .pipe__media {
    position: sticky;
    top: calc(var(--edge-h) + 1.2rem);
  }

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

  .page-about .about-coop {
    padding-top: 4.6rem;
    clip-path: polygon(0 64px, 100% 0, 100% 100%, 0 100%);
  }
}

@media (min-width: 1080px) {
  .page-about .flow {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1rem;
  }

  .page-about .tl {
    padding-left: 2.6rem;
    max-width: 56rem;
  }

  .page-about .tl__item::before {
    left: -2.06rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-btn,
  .page-about .about-link,
  .page-about .flow__detail,
  .page-about .coop__btn,
  .page-about .coop__link {
    transition: none;
  }
}