.page-about {
  --ab-rule: rgba(159, 176, 166, 0.18);
  --ab-rule-strong: rgba(159, 176, 166, 0.34);
  background: var(--ink);
  color: var(--text-ink);
  overflow-x: clip;
  display: block;
}

.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 22px 0 6px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist);
}

.page-about .breadcrumb a {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}

.page-about .breadcrumb a:hover {
  color: var(--orange);
  border-bottom-color: var(--orange);
}

.page-about .breadcrumb span[aria-hidden] {
  color: var(--green-pitch);
}

/* ---------- 首屏框景 ---------- */

.page-about .ab-hero {
  padding: 8px 0 44px;
}

.page-about .ab-frame {
  position: relative;
  border: 1px solid var(--ab-rule-strong);
  background:
    radial-gradient(120% 88% at 10% -6%, rgba(30, 91, 62, 0.5) 0%, rgba(13, 20, 18, 0) 62%),
    var(--green-night);
  padding: 42px 20px 34px;
  overflow: hidden;
}

.page-about .ab-frame::before,
.page-about .ab-frame::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 7px;
  background-image: repeating-linear-gradient(to right, var(--green-pitch) 0 1px, transparent 1px 26px);
  opacity: 0.9;
}

.page-about .ab-frame::before {
  top: 0;
}

.page-about .ab-frame::after {
  bottom: 0;
}

.page-about .ab-frame__spot {
  position: absolute;
  top: -56px;
  right: -56px;
  width: 180px;
  height: 180px;
  border-radius: 50%;
  border: 1px solid rgba(30, 91, 62, 0.6);
  pointer-events: none;
}

.page-about .ab-frame__spot::after {
  content: "";
  position: absolute;
  inset: 64px;
  border-radius: 50%;
  border: 1px solid rgba(255, 122, 26, 0.28);
}

.page-about .ab-hero__kicker {
  color: var(--orange);
  margin: 0 0 18px;
}

.page-about .ab-hero__title {
  margin: 0;
  font-size: clamp(34px, 7.2vw, 74px);
  font-weight: 200;
  line-height: 1.08;
  letter-spacing: 0.005em;
  color: var(--paper);
  max-width: 15em;
}

.page-about .ab-hero__lede {
  margin: 24px 0 0;
  max-width: 620px;
  font-size: 16px;
  line-height: 1.9;
  color: var(--text-ink-soft);
}

.page-about .ab-keys {
  list-style: none;
  margin: 38px 0 0;
  padding: 24px 0 0;
  border-top: 1px solid var(--ab-rule);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px 18px;
}

.page-about .ab-key__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 34px;
  line-height: 1;
  color: var(--blue);
}

.page-about .ab-key__txt {
  display: block;
  margin-top: 9px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--mist);
}

/* ---------- 画布与索引 ---------- */

.page-about .ab-canvas {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  padding-bottom: 72px;
}

.page-about .ab-rail {
  position: static;
  margin-bottom: 12px;
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 0;
  padding: 12px 0;
  display: flex;
  gap: 20px;
  overflow-x: auto;
  scrollbar-width: none;
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .ab-rail__list::-webkit-scrollbar {
  display: none;
}

.page-about .ab-rail a {
  display: flex;
  align-items: baseline;
  gap: 7px;
  padding: 4px 0;
  text-decoration: none;
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  transition: color var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease);
}

.page-about .ab-rail__no {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--green-pitch);
}

.page-about .ab-rail__tx {
  font-size: 13px;
  color: var(--mist);
}

.page-about .ab-rail a:hover .ab-rail__tx {
  color: var(--paper);
}

.page-about .ab-rail a.is-active {
  border-bottom-color: var(--orange);
}

.page-about .ab-rail a.is-active .ab-rail__no {
  color: var(--orange);
}

.page-about .ab-rail a.is-active .ab-rail__tx {
  color: var(--paper);
}

/* ---------- 章节 ---------- */

.page-about .ab-flow {
  min-width: 0;
}

.page-about .ab-chapter {
  padding: 44px 0 52px;
  border-top: 1px solid var(--ab-rule);
}

.page-about .ab-chapter:first-child {
  border-top: 0;
}

.page-about .ab-chapter__body {
  max-width: 100%;
}

.page-about .ab-kicker {
  margin: 0 0 14px;
  color: var(--mist);
}

.page-about .ab-chapter__title {
  margin: 0 0 22px;
  font-size: clamp(27px, 4.6vw, 46px);
  font-weight: 200;
  line-height: 1.18;
  color: var(--paper);
  max-width: 18em;
}

.page-about .ab-chapter p {
  margin: 0 0 1.2em;
  font-size: 16px;
  line-height: 1.88;
  color: var(--text-ink-soft);
}

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

.page-about .ab-chapter a {
  color: var(--blue);
  text-decoration: none;
  border-bottom: 1px solid rgba(59, 201, 245, 0.4);
  transition: border-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}

.page-about .ab-chapter a:hover {
  color: var(--orange);
  border-bottom-color: var(--orange);
}

/* ---------- 暖纸说明牌 ---------- */

.page-about .ab-slab {
  margin-top: 30px;
  padding: 22px 20px 20px;
  background: var(--paper);
  border-left: 2px solid var(--orange);
  color: var(--text-paper);
}

.page-about .ab-slab__k {
  margin: 0 0 10px !important;
  font-size: 12px !important;
  font-weight: 500;
  letter-spacing: 0.12em;
  color: var(--orange) !important;
  text-transform: none;
}

.page-about .ab-slab__v {
  margin: 0 0 10px !important;
  font-size: 17px !important;
  line-height: 1.7 !important;
  color: var(--text-paper) !important;
}

.page-about .ab-slab__note {
  margin: 0 !important;
  font-size: 14px !important;
  line-height: 1.75 !important;
  color: var(--text-paper-soft) !important;
}

/* ---------- 图片 ---------- */

.page-about .ab-figure {
  margin: 32px 0 0;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--ab-rule);
}

.page-about .ab-figure .media-frame {
  overflow: hidden;
}

.page-about .ab-figure .media-caption {
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

.page-about .ab-figure--tall img {
  object-position: center;
}

/* ---------- 折叠组 ---------- */

.page-about .ab-folds {
  margin-top: 34px;
}

.page-about .fold {
  border-top: 1px solid var(--ab-rule);
}

.page-about .fold:last-child {
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .fold-head {
  width: 100%;
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 18px 2px;
  background: none;
  border: 0;
  font-family: inherit;
  font-size: 16px;
  color: var(--paper);
  text-align: left;
  cursor: pointer;
  transition: color var(--dur-fast) var(--ease);
}

.page-about .fold-head:hover {
  color: var(--orange);
}

.page-about .fold-head:focus-visible {
  outline: 1px solid var(--blue);
  outline-offset: 2px;
}

.page-about .ab-fold__title {
  flex: none;
  font-size: 16px;
  color: inherit;
}

.page-about .ab-fold__brief {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 13px;
  color: var(--mist);
  line-height: 1.5;
}

.page-about .fold-arrow {
  flex: none;
  align-self: center;
  width: 8px;
  height: 8px;
  margin-left: auto;
  border-right: 1px solid var(--mist);
  border-bottom: 1px solid var(--mist);
  transform: rotate(45deg) translate(-2px, -2px);
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .fold[data-open="true"] .fold-arrow {
  transform: rotate(-135deg) translate(-2px, -2px);
  border-color: var(--orange);
}

.page-about .fold-body {
  overflow: hidden;
  max-height: 640px;
  opacity: 1;
  transition: max-height var(--dur) var(--ease), opacity var(--dur) var(--ease);
}

.page-about .fold-body p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.82;
  color: var(--text-ink-soft);
}

.page-about .fold-body p:last-child {
  margin-bottom: 20px;
}

.js .page-about .fold[data-open="false"] > .fold-body {
  max-height: 0;
  opacity: 0;
}

.js .page-about .fold[data-open="false"] > .fold-body p {
  margin-bottom: 0;
}

/* ---------- 五步刻度 ---------- */

.page-about .ab-process__lead {
  margin-top: 30px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 24px;
}

.page-about .ab-process__lead .ab-figure {
  margin: 0;
}

.page-about .ab-process__leadtext p {
  margin: 0 0 1.1em;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist);
}

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

.page-about .ab-steps {
  list-style: none;
  margin: 40px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
}

.page-about .ab-step {
  position: relative;
  padding-top: 22px;
  border-top: 1px solid var(--green-pitch);
}

.page-about .ab-step::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--ink);
  border: 1px solid var(--orange);
}

.page-about .ab-step .fold {
  border-top: 0;
}

.page-about .ab-step:last-child .fold {
  border-bottom: 0;
}

.page-about .ab-step__head {
  padding: 10px 0 12px;
  gap: 9px;
  align-items: baseline;
}

.page-about .ab-step__no {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--orange);
}

.page-about .ab-step__name {
  font-size: 16px;
  color: var(--paper);
}

.page-about .ab-step .fold-arrow {
  align-self: center;
}

.page-about .ab-step .fold-body p {
  font-size: 14px;
  line-height: 1.78;
}

.page-about .ab-step__meta {
  font-family: var(--font-mono);
  font-size: 12px !important;
  letter-spacing: 0.06em;
  color: var(--blue) !important;
}

/* ---------- 使用者 ---------- */

.page-about .ab-users {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 26px;
}

.page-about .ab-user {
  padding-left: 16px;
  border-left: 1px solid var(--green-pitch);
}

.page-about .ab-user__title {
  margin: 0 0 10px;
  font-size: 18px;
  font-weight: 500;
  color: var(--paper);
}

.page-about .ab-user__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-ink-soft);
}

.page-about .ab-users__tail {
  margin: 30px 0 0;
  padding-top: 20px;
  border-top: 1px solid var(--ab-rule);
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist);
}

/* ---------- 收尾 ---------- */

.page-about .ab-chapter--final {
  padding-bottom: 24px;
}

.page-about .ab-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 32px;
}

.page-about .ab-actions__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 26px;
  margin-top: 26px !important;
  padding-top: 20px;
  border-top: 1px solid var(--ab-rule);
}

.page-about .ab-actions__links a {
  font-size: 13px;
}

/* ---------- 媒体查询 ---------- */

@media (min-width: 640px) {
  .page-about .ab-frame {
    padding: 56px 40px 46px;
  }

  .page-about .ab-frame__spot {
    width: 260px;
    height: 260px;
    top: -90px;
    right: -80px;
  }

  .page-about .ab-frame__spot::after {
    inset: 92px;
  }

  .page-about .ab-keys {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 22px 24px;
  }

  .page-about .ab-chapter {
    padding: 56px 0 64px;
  }

  .page-about .ab-users {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 24px;
  }

  .page-about .ab-user {
    padding-left: 18px;
  }

  .page-about .ab-process__lead {
    grid-template-columns: 240px minmax(0, 1fr);
    gap: 32px;
    align-items: start;
  }
}

@media (min-width: 900px) {
  .page-about .ab-steps {
    grid-template-columns: repeat(5, minmax(0, 1fr));
    gap: 0;
  }

  .page-about .ab-step {
    padding-right: 18px;
  }

  .page-about .ab-step:last-child {
    padding-right: 0;
  }

  .page-about .ab-users {
    grid-template-columns: 1.15fr 0.85fr 1fr;
    gap: 34px;
  }
}

@media (min-width: 1000px) {
  .page-about .ab-canvas {
    grid-template-columns: 92px minmax(0, 1fr);
    column-gap: 44px;
    align-items: start;
  }

  .page-about .ab-rail {
    position: sticky;
    top: 104px;
    margin-bottom: 0;
  }

  .page-about .ab-rail__list {
    flex-direction: column;
    gap: 2px;
    padding: 4px 0;
    overflow: visible;
    border-bottom: 0;
  }

  .page-about .ab-rail a {
    border-bottom: 0;
    border-left: 2px solid transparent;
    padding: 7px 0 7px 10px;
  }

  .page-about .ab-rail a.is-active {
    border-bottom-color: transparent;
    border-left-color: var(--orange);
  }

  .page-about .ab-rail__tx {
    display: block;
    font-size: 13px;
  }

  .page-about .ab-rail a {
    flex-direction: column;
    align-items: flex-start;
    gap: 3px;
  }

  .page-about .ab-chapter__body {
    max-width: 680px;
  }

  .page-about .ab-chapter--right .ab-chapter__body {
    margin-left: auto;
    margin-right: 0;
  }

  .page-about .ab-chapter--left .ab-chapter__body {
    margin-left: 0;
    margin-right: auto;
  }

  .page-about .ab-chapter--final .ab-chapter__body {
    max-width: 760px;
  }

  .page-about .ab-process__lead {
    grid-template-columns: 280px minmax(0, 1fr);
    gap: 44px;
  }
}

@media (min-width: 1200px) {
  .page-about .ab-chapter--right .ab-chapter__body {
    padding-right: 8px;
  }
}
</