.page-about {
  --about-line: rgba(31, 224, 200, 0.2);
  --about-surface: rgba(16, 41, 76, 0.6);
  --about-surface-strong: rgba(16, 41, 76, 0.88);
  display: block;
}

/* ---------- 首屏塔式 ---------- */
.page-about__masthead {
  position: relative;
  padding: clamp(28px, 5vw, 64px) 0 clamp(44px, 7vw, 88px);
  background:
    radial-gradient(circle at 84% 8%, rgba(31, 224, 200, 0.1), transparent 46%),
    linear-gradient(180deg, rgba(16, 41, 76, 0.6), rgba(11, 30, 58, 0) 78%);
  border-bottom: 1px solid var(--yb-line-faint);
}

.page-about .about-masthead__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

@media (min-width: 992px) {
  .page-about .about-masthead__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 56px;
    align-items: end;
  }
}

.page-about .about-masthead__title {
  margin: 14px 0 22px;
  font-size: clamp(34px, 6.2vw, 84px);
  font-weight: 300;
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--yb-paper);
}

.page-about .about-masthead__lead .yb-lede {
  max-width: 38em;
  color: var(--yb-steel);
}

.page-about .about-masthead__aside {
  padding: 20px 20px 22px;
  background: rgba(7, 18, 39, 0.78);
  border: 1px solid var(--about-line);
  clip-path: var(--yb-cut-rb);
  box-shadow: var(--yb-shadow-up);
}

.page-about .about-boundary-list {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 9px;
}

.page-about .about-boundary-list li {
  position: relative;
  padding-left: 22px;
  font-size: 15px;
  line-height: 1.7;
  color: var(--yb-steel);
}

.page-about .about-boundary-list li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 0.7em;
  width: 11px;
  height: 1px;
  background: var(--yb-red);
  transform: rotate(-18deg);
}

.page-about .about-masthead__note {
  margin: 18px 0 0;
  padding-top: 14px;
  border-top: 1px solid var(--yb-line-faint);
  font-size: 13px;
  line-height: 1.75;
  color: var(--yb-mute);
}

/* ---------- 侧栏式两栏 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
}

@media (min-width: 992px) {
  .page-about .about-layout {
    grid-template-columns: minmax(0, 3fr) minmax(0, 8fr);
    gap: 56px;
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 92px;
    max-height: calc(100vh - 128px);
    overflow-y: auto;
    padding-right: 4px;
  }
}

.page-about .yb-toc__list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .yb-toc__list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 10px 8px 12px;
  border-left: 2px solid transparent;
  color: var(--yb-mute);
  font-size: 14px;
  line-height: 1.5;
  text-decoration: none;
  transition: color 160ms var(--yb-ease), border-color 160ms var(--yb-ease), background 160ms var(--yb-ease);
}

.page-about .yb-toc__list a:hover,
.page-about .yb-toc__list a:focus-visible {
  color: var(--yb-paper);
  background: rgba(31, 224, 200, 0.06);
}

.page-about .yb-toc__list a[aria-current="true"] {
  color: var(--yb-signal);
  border-left-color: var(--yb-signal);
  background: rgba(31, 224, 200, 0.08);
}

.page-about .about-rail__no {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--yb-mute);
}

.page-about .yb-toc__list a[aria-current="true"] .about-rail__no {
  color: var(--yb-signal);
}

/* ---------- 侧栏编号卡 ---------- */
.page-about .about-idcard {
  margin-top: 28px;
  padding: 18px;
  background: var(--yb-abyss);
  border: 1px solid var(--yb-line-soft);
  clip-path: var(--yb-cut-lt);
}

.page-about .about-idcard__code {
  margin: 10px 0 8px;
  font-size: 17px;
  letter-spacing: 0.04em;
  color: var(--yb-signal);
  word-break: break-all;
}

.page-about .about-idcard__hint {
  margin: 0 0 14px;
  font-size: 12px;
  line-height: 1.65;
  color: var(--yb-mute);
}

.page-about .about-idcard__copy {
  display: block;
  width: 100%;
  min-height: 40px;
  padding: 10px 14px;
  font-family: inherit;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--yb-signal);
  background: transparent;
  border: 1px solid var(--yb-line);
  border-radius: 0;
  cursor: pointer;
  transition: background 160ms var(--yb-ease), border-color 160ms var(--yb-ease);
}

.page-about .about-idcard__copy:hover,
.page-about .about-idcard__copy:focus-visible {
  background: rgba(31, 224, 200, 0.1);
  border-color: var(--yb-signal);
}

.page-about .about-idcard__copy[data-copied="true"] {
  color: var(--yb-ink);
  background: var(--yb-signal);
}

/* ---------- 正文区块 ---------- */
.page-about .about-block + .about-block {
  margin-top: clamp(48px, 7vw, 88px);
}

.page-about .about-block + .about-block::before {
  content: "";
  display: block;
  width: 72px;
  height: 8px;
  margin-bottom: clamp(32px, 4.5vw, 48px);
  background-image: repeating-linear-gradient(-18deg, rgba(31, 224, 200, 0.5) 0 1px, transparent 1px 8px);
}

.page-about .about-block__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 20px;
  padding-top: 4px;
  border-top: 1px solid var(--yb-line);
}

.page-about .about-block__index {
  flex: 0 0 auto;
  margin: 0;
  padding-top: 6px;
  font-size: 13px;
  letter-spacing: 0.16em;
  color: var(--yb-mute);
}

.page-about .about-block__title {
  margin: 0;
  font-size: clamp(24px, 3.4vw, 40px);
  font-weight: 600;
  line-height: 1.2;
  color: var(--yb-paper);
}

.page-about .about-block > p {
  max-width: 40em;
  margin: 0 0 18px;
  color: var(--yb-steel);
  font-size: 17px;
  line-height: 1.85;
}

.page-about .about-block > p a {
  color: var(--yb-signal);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .yb-quick-read {
  margin-top: 4px;
  color: var(--yb-mute);
  font-size: 14px;
  line-height: 1.7;
}

.page-about .yb-mono {
  font-family: var(--yb-font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
}

/* ---------- 四组角色 ---------- */
.page-about .about-roles {
  list-style: none;
  margin: 26px 0 22px;
  padding: 0;
  display: grid;
  gap: 12px;
}

@media (min-width: 768px) {
  .page-about .about-roles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.page-about .about-role {
  padding: 20px;
  background: var(--about-surface);
  border: 1px solid var(--yb-line-soft);
  clip-path: var(--yb-cut-lt);
  transition: background 160ms var(--yb-ease), border-color 160ms var(--yb-ease);
}

.page-about .about-role:nth-child(even) {
  clip-path: var(--yb-cut-rb);
}

.page-about .about-role:hover {
  background: var(--about-surface-strong);
  border-color: var(--about-line);
}

.page-about .about-role__name {
  margin: 10px 0 8px;
  font-size: 19px;
  font-weight: 500;
  line-height: 1.35;
  color: var(--yb-paper);
}

.page-about .about-role__desc {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--yb-steel);
}

/* ---------- 编号拆解带 ---------- */
.page-about .about-codeband {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  margin: 28px 0;
  background: var(--yb-line-faint);
  border-top: 1px solid var(--yb-line);
  border-bottom: 1px solid var(--yb-line);
}

@media (min-width: 640px) {
  .page-about .about-codeband {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .about-codeband__cell {
  padding: 20px 16px 22px;
  background: var(--yb-abyss);
}

.page-about .about-codeband__cell:nth-child(even) {
  background: var(--yb-room);
}

.page-about .about-codeband__seg {
  margin: 0 0 10px;
  font-size: clamp(22px, 3vw, 32px);
  line-height: 1;
  color: var(--yb-signal);
  word-break: break-all;
}

.page-about .about-codeband__note {
  margin: 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--yb-mute);
}

/* ---------- 校对流程 ---------- */
.page-about .about-proof__banner {
  margin: 0 0 26px;
}

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

.page-about .about-stages {
  list-style: none;
  margin: 24px 0 28px;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .about-stage {
  background: var(--about-surface);
  border: 1px solid var(--yb-line-soft);
  clip-path: var(--yb-cut-lt);
}

.page-about .about-stage summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 12px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
  border-left: 2px solid var(--yb-signal);
}

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

.page-about .about-stage summary:focus-visible {
  outline: 1px solid var(--yb-signal);
  outline-offset: 2px;
}

.page-about .about-stage__no {
  font-size: 13px;
  color: var(--yb-signal);
}

.page-about .about-stage__name {
  font-size: 19px;
  font-weight: 500;
  color: var(--yb-paper);
}

.page-about .about-stage__meta {
  margin-left: auto;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--yb-mute);
}

.page-about .about-stage__body {
  padding: 0 18px 18px;
  border-top: 1px solid var(--yb-line-faint);
}

.page-about .about-stage__body p {
  margin: 14px 0 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--yb-steel);
  max-width: 40em;
}

/* ---------- 引文 + 竖图 ---------- */
.page-about .about-proof__split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  align-items: start;
  margin-bottom: 24px;
}

@media (min-width: 768px) {
  .page-about .about-proof__split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    gap: 24px;
  }
}

.page-about .about-quote {
  padding: 24px 22px 22px;
}

.page-about .about-quote__title {
  margin: 0 0 14px;
  font-size: 14px;
  letter-spacing: 0.1em;
  font-family: var(--yb-font-sans);
  color: var(--yb-red);
}

.page-about .about-quote__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .about-quote__list li {
  position: relative;
  padding-left: 16px;
  font-size: 16px;
  line-height: 1.9;
  color: var(--yb-ink);
}

.page-about .about-quote__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.85em;
  width: 8px;
  height: 1px;
  background: var(--yb-ink);
  opacity: 0.5;
}

.page-about .about-quote__foot {
  margin: 18px 0 0;
  padding-top: 12px;
  border-top: 1px solid rgba(26, 20, 15, 0.18);
  font-size: 13px;
  line-height: 1.7;
  color: rgba(26, 20, 15, 0.7);
}

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

/* ---------- 规模数字 ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 26px 0 26px;
  background: var(--yb-line-faint);
  border-top: 1px solid var(--yb-line);
  border-bottom: 1px solid var(--yb-line);
}

@media (min-width: 768px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

.page-about .about-stat {
  padding: 24px 18px 22px;
  background: var(--yb-deep);
}

.page-about .about-stat__num {
  margin: 0;
  font-size: clamp(30px, 4.2vw, 50px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--yb-signal);
}

.page-about .about-stat__label {
  margin: 12px 0 0;
  font-size: 13px;
  line-height: 1.65;
  color: var(--yb-steel);
}

.page-about .about-rhythm {
  list-style: none;
  margin: 0 0 22px;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-rhythm li {
  padding-left: 16px;
  border-left: 1px solid var(--yb-line);
  font-size: 15px;
  line-height: 1.85;
  color: var(--yb-steel);
}

.page-about .about-rhythm li .yb-mono {
  display: inline-block;
  margin-right: 8px;
  color: var(--yb-signal);
}

/* ---------- 来源与边界 ---------- */
.page-about .about-source-tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 22px 0 26px;
  padding: 0;
}

.page-about .about-compare {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin: 0 0 26px;
}

@media (min-width: 640px) {
  .page-about .about-compare {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 16px;
  }
}

.page-about .about-compare__col {
  padding: 20px;
}

.page-about .about-compare__col--do {
  background: rgba(31, 224, 200, 0.07);
  border: 1px solid rgba(31, 224, 200, 0.28);
  clip-path: var(--yb-cut-lt);
}

.page-about .about-compare__col--dont {
  background: rgba(214, 67, 47, 0.08);
  border: 1px solid rgba(214, 67, 47, 0.32);
  clip-path: var(--yb-cut-rb);
}

.page-about .about-compare__label--no {
  color: var(--yb-red);
}

.page-about .about-compare__col ul {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 9px;
}

.page-about .about-compare__col li {
  position: relative;
  padding-left: 16px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--yb-steel);
}

.page-about .about-compare__col li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.75em;
  width: 8px;
  height: 1px;
}

.page-about .about-compare__col--do li::before {
  background: var(--yb-signal);
}

.page-about .about-compare__col--dont li::before {
  background: var(--yb-red);
}

/* ---------- 写作方式 ---------- */
.page-about .about-voice {
  list-style: none;
  margin: 26px 0 24px;
  padding: 0;
  display: grid;
  gap: 20px;
}

@media (min-width: 768px) {
  .page-about .about-voice {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 24px;
  }

  .page-about .about-voice li:nth-child(2) {
    margin-top: 20px;
  }

  .page-about .about-voice li:nth-child(3) {
    margin-top: 40px;
  }
}

.page-about .about-voice li {
  padding-top: 18px;
  border-top: 1px solid var(--yb-line);
}

.page-about .about-voice__no {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--yb-mute);
}

.page-about .about-voice__name {
  margin: 0 0 10px;
  font-size: 19px;
  font-weight: 500;
  line-height: 1.35;
  color: var(--yb-paper);
}

.page-about .about-voice li > p:last-child {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--yb-steel);
}

/* ---------- 底部归属 ---------- */
.page-about__base {
  border-top: 1px solid var(--yb-line-faint);
}

.page-about .about-base__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 26px;
  align-items: center;
}

@media (min-width: 768px) {
  .page-about .about-base__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: 44px;
  }
}

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

.page-about .about-base__title {
  margin: 12px 0 16px;
  font-size: clamp(22px, 2.8vw, 32px);
  font-weight: 600;
  line-height: 1.25;
  color: var(--yb-paper);
}

.page-about .about-base__text p {
  max-width: 40em;
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--yb-steel);
}

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

.page-about .about-base__text a {
  color: var(--yb-signal);
  text-decoration: underline;
  text-underline-offset: 3px;
}

@media (prefers-reduced-motion: reduce) {
  .page-about .yb-toc__list a,
  .page-about .about-role,
  .page-about .about-idcard__copy {
    transition-duration: 0.01ms;
  }
}