.page-about {
  background: var(--ink);
  color: var(--paper);
  --about-card: rgba(44, 50, 56, 0.42);
  --about-cut: polygon(0 0, 100% 0, 100% calc(100% - 16px), calc(100% - 16px) 100%, 0 100%);
}

.page-about .breadcrumb {
  padding: 1.6rem 0 0.4rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  color: var(--steel);
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.page-about .breadcrumb a {
  color: var(--steel);
  text-decoration: none;
  transition: color 0.2s var(--ease);
}

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

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: 2rem 0 3.6rem;
  background:
    radial-gradient(900px 460px at 88% -12%, rgba(255, 77, 26, 0.24), transparent 62%),
    radial-gradient(680px 420px at 4% 112%, rgba(0, 229, 255, 0.11), transparent 62%),
    linear-gradient(158deg, var(--ink) 0%, var(--teal-black) 100%);
}

.page-about .about-hero__grid {
  display: grid;
  gap: 2.2rem;
}

.page-about .about-hero__title {
  margin: 0.9rem 0 0;
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 8.2vw, 4.4rem);
  font-weight: 300;
  line-height: 1.02;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .about-hero__title em {
  display: inline-block;
  font-style: normal;
  font-weight: 800;
  color: var(--flame);
  transform: skewX(-6deg);
  transform-origin: left bottom;
}

.page-about .about-hero__lead {
  margin: 1.3rem 0 0;
  max-width: 52ch;
  font-size: 1rem;
  line-height: 1.75;
  color: rgba(244, 241, 234, 0.82);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.7rem;
  margin-top: 1.8rem;
}

.page-about .about-hero__index {
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem 2.2rem;
  margin: 2.2rem 0 0;
  padding-top: 1.3rem;
  border-top: 1px solid var(--line);
}

.page-about .about-hero__index dt {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.2em;
  color: var(--steel);
}

.page-about .about-hero__index dd {
  margin: 0.3rem 0 0;
  font-family: var(--font-mono);
  font-size: 1.7rem;
  line-height: 1;
  color: var(--paper);
}

.page-about .about-hero__index > div:nth-child(1) dd { color: var(--flame); }
.page-about .about-hero__index > div:nth-child(2) dd { color: var(--cyan); }
.page-about .about-hero__index > div:nth-child(3) dd { color: var(--ember); }

.page-about .about-hero__visual {
  position: relative;
  margin: 0;
}

.page-about .about-hero__visual img {
  display: block;
  width: 100%;
  height: auto;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 34px), calc(100% - 34px) 100%, 0 100%);
  filter: saturate(0.92) contrast(1.06);
}

.page-about .about-hero__visual figcaption {
  margin-top: 0.8rem;
  font-size: 0.78rem;
  color: var(--steel);
  display: flex;
  align-items: baseline;
  gap: 0.6rem;
}

.page-about .about-hero__visual figcaption .mono {
  color: var(--cyan);
  letter-spacing: 0.14em;
}

/* ---------- 章节骨架 ---------- */
.page-about .about-chapter {
  position: relative;
  padding: 3.6rem 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-chapter--wine { background: linear-gradient(180deg, var(--wine-black) 0%, var(--ink) 92%); }
.page-about .about-chapter--teal { background: linear-gradient(180deg, var(--teal-black) 0%, var(--ink) 92%); }
.page-about .about-chapter--indigo { background: linear-gradient(180deg, var(--indigo-black) 0%, var(--ink) 92%); }

.page-about .about-chapter__head {
  display: grid;
  gap: 0.8rem;
  margin-bottom: 2.4rem;
}

.page-about .about-chapter__num {
  font-family: var(--font-display);
  font-size: clamp(3.2rem, 9vw, 5.6rem);
  font-weight: 300;
  line-height: 0.78;
  letter-spacing: -0.03em;
  color: transparent;
  -webkit-text-stroke: 1px rgba(244, 241, 234, 0.32);
}

.page-about .about-chapter__headtext .section__title {
  margin: 0.5rem 0 0;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 4.6vw, 2.5rem);
  font-weight: 700;
  line-height: 1.16;
  color: var(--paper);
}

.page-about .about-chapter__headtext .section__lead {
  margin: 0.9rem 0 0;
  max-width: 62ch;
  font-size: 0.96rem;
  line-height: 1.8;
  color: rgba(244, 241, 234, 0.74);
}

/* ---------- 01 时间线 ---------- */
.page-about .about-timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 2.6rem;
  position: relative;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 0.55rem;
  bottom: 0.8rem;
  width: 2px;
  background: linear-gradient(180deg, var(--flame) 0%, rgba(255, 77, 26, 0.28) 58%, transparent 100%);
}

.page-about .about-timeline__item {
  position: relative;
  padding-bottom: 2rem;
}

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

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -2.6rem;
  top: 0.25rem;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 2px solid var(--flame);
  background: var(--ink);
  box-shadow: 0 0 0 5px rgba(255, 77, 26, 0.13);
}

.page-about .about-timeline__mark {
  display: inline-block;
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  color: var(--ember);
  padding: 0.14rem 0.5rem;
  border: 1px solid rgba(255, 176, 138, 0.34);
}

.page-about .about-timeline__item h3 {
  margin: 0.6rem 0 0.4rem;
  font-family: var(--font-display);
  font-size: 1.32rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-timeline__item p {
  margin: 0;
  max-width: 60ch;
  font-size: 0.92rem;
  line-height: 1.85;
  color: rgba(244, 241, 234, 0.76);
}

/* ---------- 02 版本折叠 ---------- */
.page-about .about-versions {
  display: grid;
  gap: 0.8rem;
}

.page-about .about-versions__item {
  background: var(--about-card);
  border: 1px solid var(--line);
  border-left: 3px solid var(--flame);
  clip-path: var(--about-cut);
  transition: border-color 0.25s var(--ease), background 0.25s var(--ease);
}

.page-about .about-versions__item[open] {
  border-left-color: var(--cyan);
  background: rgba(44, 50, 56, 0.66);
}

.page-about .about-versions__item summary {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 0.9rem;
  padding: 0.95rem 1.15rem;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-versions__item summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1.1rem;
  line-height: 1;
  color: var(--flame);
}

.page-about .about-versions__item[open] summary::after {
  content: "–";
  color: var(--cyan);
}

.page-about .about-versions__code {
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  color: var(--cyan);
  white-space: nowrap;
}

.page-about .about-versions__name {
  font-family: var(--font-display);
  font-size: 1.06rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-versions__panel {
  padding: 0 1.15rem 1.15rem;
}

.page-about .about-versions__panel p {
  margin: 0;
  max-width: 62ch;
  font-size: 0.9rem;
  line-height: 1.85;
  color: rgba(244, 241, 234, 0.76);
}

.page-about .about-versions__figure {
  margin: 2.2rem 0 0;
}

.page-about .about-versions__figure img {
  display: block;
  width: 100%;
  height: auto;
  clip-path: var(--about-cut);
}

.page-about .about-versions__figure figcaption {
  margin-top: 0.75rem;
  font-size: 0.78rem;
  color: var(--steel);
  display: flex;
  gap: 0.6rem;
  align-items: baseline;
}

.page-about .about-versions__figure figcaption .mono {
  color: var(--cyan);
  letter-spacing: 0.14em;
}

/* ---------- 03 数据校验 ---------- */
.page-about .about-check {
  display: grid;
  gap: 2rem;
}

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

.page-about .about-flow__step {
  position: relative;
  padding-left: 3.1rem;
}

.page-about .about-flow__step::before {
  content: "";
  position: absolute;
  left: 1.02rem;
  top: 2.3rem;
  bottom: -1.5rem;
  width: 2px;
  background: linear-gradient(180deg, rgba(0, 229, 255, 0.66), rgba(0, 229, 255, 0.06));
}

.page-about .about-flow__step:last-child::before { display: none; }

.page-about .about-flow__no {
  position: absolute;
  left: 0;
  top: 0;
  width: 2.1rem;
  height: 2.1rem;
  display: grid;
  place-items: center;
  font-size: 0.74rem;
  color: var(--cyan);
  border: 1px solid rgba(0, 229, 255, 0.45);
  border-radius: 50%;
  background: rgba(11, 31, 36, 0.85);
}

.page-about .about-flow__step h3 {
  margin: 0.42rem 0 0.35rem;
  font-family: var(--font-display);
  font-size: 1.18rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-flow__step p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.8;
  color: rgba(244, 241, 234, 0.74);
}

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

.page-about .about-check__figure img {
  display: block;
  width: 100%;
  height: auto;
  clip-path: polygon(0 0, 100% 0, 100% 100%, 28px 100%, 0 calc(100% - 28px));
}

.page-about .about-check__figure figcaption {
  margin-top: 0.75rem;
  font-size: 0.78rem;
  color: var(--steel);
  display: flex;
  gap: 0.6rem;
  align-items: baseline;
}

.page-about .about-check__figure figcaption .mono {
  color: var(--cyan);
  letter-spacing: 0.14em;
}

.page-about .about-check__note {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  margin: 2rem 0 0;
  padding: 1rem 1.15rem;
  font-size: 0.88rem;
  line-height: 1.75;
  color: rgba(244, 241, 234, 0.78);
  background: rgba(0, 229, 255, 0.06);
  border-left: 2px solid var(--cyan);
}

.page-about .about-check__note .status-dot {
  margin-top: 0.5rem;
  flex: none;
}

/* ---------- 04 团队 ---------- */
.page-about .about-crew__stats {
  list-style: none;
  margin: 0 0 2.4rem;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.7rem;
}

.page-about .about-crew__stats li {
  padding: 1rem 0.8rem;
  background: var(--about-card);
  border-bottom: 2px solid var(--line-strong);
  clip-path: var(--about-cut);
}

.page-about .about-crew__stats li:nth-child(1) { border-bottom-color: var(--flame); }
.page-about .about-crew__stats li:nth-child(2) { border-bottom-color: var(--cyan); }
.page-about .about-crew__stats li:nth-child(3) { border-bottom-color: var(--ember); }

.page-about .about-crew__num {
  display: block;
  font-size: clamp(1.7rem, 6vw, 2.5rem);
  line-height: 1;
  color: var(--paper);
}

.page-about .about-crew__stats li:nth-child(1) .about-crew__num { color: var(--flame); }
.page-about .about-crew__stats li:nth-child(2) .about-crew__num { color: var(--cyan); }
.page-about .about-crew__stats li:nth-child(3) .about-crew__num { color: var(--ember); }

.page-about .about-crew__label {
  display: block;
  margin-top: 0.5rem;
  font-size: 0.72rem;
  line-height: 1.5;
  color: var(--steel);
}

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

.page-about .about-crew__line li {
  position: relative;
  padding-left: 1.6rem;
}

.page-about .about-crew__line li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55rem;
  width: 0.55rem;
  height: 0.55rem;
  border-radius: 50%;
  background: var(--flame);
  box-shadow: 0 0 0 4px rgba(255, 77, 26, 0.16);
}

.page-about .about-crew__city {
  display: block;
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-crew__role {
  display: block;
  margin-top: 0.25rem;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .about-crew__note {
  margin: 2rem 0 0;
  max-width: 66ch;
  font-size: 0.9rem;
  line-height: 1.85;
  color: rgba(244, 241, 234, 0.72);
}

/* ---------- 05 生态 ---------- */
.page-about .about-eco {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.9rem;
}

.page-about .about-eco__chip {
  padding: 1.1rem 1.2rem;
  background: var(--about-card);
  border-top: 2px solid var(--line-strong);
  clip-path: var(--about-cut);
}

.page-about .about-eco__chip:nth-child(1) { border-top-color: var(--flame); }
.page-about .about-eco__chip:nth-child(2) { border-top-color: var(--cyan); }
.page-about .about-eco__chip:nth-child(3) { border-top-color: var(--ember); }

.page-about .about-eco__n {
  display: block;
  font-size: clamp(1.9rem, 7vw, 2.8rem);
  line-height: 1;
  color: var(--paper);
}

.page-about .about-eco__chip:nth-child(1) .about-eco__n { color: var(--flame); }
.page-about .about-eco__chip:nth-child(2) .about-eco__n { color: var(--cyan); }
.page-about .about-eco__chip:nth-child(3) .about-eco__n { color: var(--ember); }

.page-about .about-eco__t {
  display: block;
  margin-top: 0.35rem;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-eco__chip p {
  margin: 0.6rem 0 0;
  font-size: 0.87rem;
  line-height: 1.8;
  color: rgba(244, 241, 234, 0.72);
}

.page-about .about-eco__honor {
  margin-top: 2rem;
  padding: 1.3rem 1.2rem;
  border: 1px solid var(--line);
  border-left: 3px solid var(--flame);
  display: grid;
  gap: 0.7rem;
}

.page-about .about-eco__honor p {
  margin: 0;
  max-width: 66ch;
  font-size: 0.9rem;
  line-height: 1.85;
  color: rgba(244, 241, 234, 0.76);
}

/* ---------- 06 原则 ---------- */
.page-about .about-principles {
  display: grid;
  gap: 1rem;
}

.page-about .about-principles__card {
  background: var(--paper);
  color: var(--ink);
  padding: 1.4rem 1.3rem;
  clip-path: var(--about-cut);
  box-shadow: 7px 7px 0 rgba(255, 77, 26, 0.26);
}

.page-about .about-principles__no {
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  color: #b23a10;
}

.page-about .about-principles__card h3 {
  margin: 0.5rem 0 0.55rem;
  font-family: var(--font-display);
  font-size: 1.24rem;
  font-weight: 700;
  color: var(--ink);
}

.page-about .about-principles__card p {
  margin: 0;
  font-size: 0.9rem;
  line-height: 1.8;
  color: #3a4046;
}

.page-about .about-next {
  margin-top: 2.4rem;
  padding: 1.6rem 1.3rem;
  background: linear-gradient(135deg, rgba(255, 77, 26, 0.16), rgba(0, 229, 255, 0.08));
  border: 1px solid var(--line);
  clip-path: var(--about-cut);
  display: grid;
  gap: 1.3rem;
}

.page-about .about-next__copy h3 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 4vw, 1.7rem);
  font-weight: 700;
  color: var(--paper);
}

.page-about .about-next__copy p {
  margin: 0.7rem 0 0;
  max-width: 56ch;
  font-size: 0.92rem;
  line-height: 1.8;
  color: rgba(244, 241, 234, 0.8);
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .about-chapter {
    padding: 4.6rem 0;
  }

  .page-about .about-chapter__head {
    grid-template-columns: 116px 1fr;
    align-items: start;
    gap: 2rem;
    margin-bottom: 3rem;
  }

  .page-about .about-chapter__num {
    padding-top: 0.2rem;
  }

  .page-about .about-check {
    grid-template-columns: 1fr 0.85fr;
    align-items: start;
    gap: 2.4rem;
  }

  .page-about .about-check__figure {
    position: sticky;
    top: 6rem;
  }

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

  .page-about .about-principles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.2rem;
  }

  .page-about .about-principles__card:nth-child(2) {
    transform: translateY(1.2rem);
  }

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

  .page-about .about-crew__line::before {
    content: "";
    position: absolute;
    left: 0.27rem;
    right: 0.27rem;
    top: 0.82rem;
    height: 1px;
    background: linear-gradient(90deg, var(--flame), var(--cyan));
    opacity: 0.45;
  }

  .page-about .about-crew__line li {
    padding-left: 0;
    padding-top: 1.7rem;
  }

  .page-about .about-crew__line li::before {
    top: 0;
  }

  .page-about .about-next {
    grid-template-columns: 1.1fr 0.9fr;
    align-items: center;
    padding: 2rem 1.8rem;
  }

  .page-about .about-next__links {
    justify-content: flex-end;
  }
}

@media (min-width: 980px) {
  .page-about .about-hero {
    padding: 2.6rem 0 4.6rem;
  }

  .page-about .about-hero__grid {
    grid-template-columns: 1.05fr 0.95fr;
    align-items: center;
    gap: 3.2rem;
  }

  .page-about .about-hero__lead {
    font-size: 1.05rem;
  }

  .page-about .about-timeline {
    padding-left: 3.4rem;
  }

  .page-about .about-timeline__item {
    padding-bottom: 2.4rem;
  }

  .page-about .about-timeline__item::before {
    left: -3.4rem;
  }

  .page-about .about-versions__item summary {
    padding: 1.1rem 1.4rem;
  }

  .page-about .about-versions__panel {
    padding: 0 1.4rem 1.35rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-principles__card:nth-child(2) {
    transform: none;
  }

  .page-about .about-hero__title em {
    transform: none;
  }
}