.page-about {
  --about-line: rgba(21, 38, 31, 0.12);
  background: var(--yk-cream);
  color: var(--yk-ink);
  font-family: var(--yk-font-body);
}

/* 首屏框景 */
.page-about .about-hero {
  padding: clamp(20px, 4vw, 40px) 0 clamp(30px, 5vw, 56px);
  background: linear-gradient(180deg, var(--yk-sand) 0%, var(--yk-cream) 82%);
}

.page-about .about-hero__frame {
  position: relative;
  margin-top: clamp(18px, 3vw, 32px);
  padding: clamp(24px, 4.5vw, 56px) clamp(20px, 4.5vw, 56px);
  border: 2px solid var(--yk-green-deep);
  border-radius: var(--yk-radius-lg);
  background: var(--yk-cream);
  box-shadow: var(--yk-shadow-soft);
  overflow: hidden;
}

.page-about .about-hero__frame::before {
  content: "";
  position: absolute;
  inset: 0 auto auto 0;
  width: 160px;
  height: 160px;
  background: radial-gradient(circle at top left, rgba(31, 111, 74, 0.16), transparent 70%);
  pointer-events: none;
}

.page-about .about-hero__frame::after {
  content: "";
  position: absolute;
  right: clamp(18px, 4vw, 48px);
  bottom: clamp(16px, 3vw, 34px);
  width: 0;
  height: 0;
  border-left: 16px solid transparent;
  border-right: 16px solid transparent;
  border-bottom: 26px solid rgba(232, 106, 51, 0.5);
  pointer-events: none;
}

.page-about .about-hero__ticks {
  position: absolute;
  inset: 0 0 auto 0;
  height: 16px;
  background-image: repeating-linear-gradient(90deg, var(--yk-green-deep) 0 2px, transparent 2px 26px);
  opacity: 0.16;
  pointer-events: none;
}

.page-about .about-hero h1 {
  position: relative;
  margin: 14px 0 0;
  max-width: 17ch;
  font-family: var(--yk-font-display);
  font-size: clamp(30px, 6.2vw, 62px);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--yk-ink);
}

.page-about .about-hero .yk-lede {
  position: relative;
  max-width: 62ch;
  margin: clamp(14px, 2vw, 20px) 0 0;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.85;
  color: var(--yk-rock);
}

.page-about .about-hero__note {
  position: relative;
  margin: 16px 0 0;
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--yk-green);
  font-weight: 600;
}

.page-about .about-hero__actions {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(20px, 3vw, 32px);
}

/* 非对称双栏 */
.page-about .about-body {
  padding: clamp(30px, 5vw, 64px) 0 clamp(56px, 8vw, 96px);
}

.page-about .about-split {
  display: grid;
  gap: clamp(24px, 4vw, 44px);
}

.page-about .about-rail {
  padding: 6px 0 6px 16px;
  border-left: 3px solid var(--yk-green);
  border-radius: 0 var(--yk-radius-md) var(--yk-radius-md) 0;
  background: linear-gradient(90deg, rgba(31, 111, 74, 0.07), transparent 80%);
}

.page-about .about-rail__title {
  margin: 0 0 10px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.2em;
  color: var(--yk-green);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 4px;
}

.page-about .about-rail__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 12px;
  border-radius: var(--yk-radius-pill);
  font-size: 15px;
  font-weight: 600;
  color: var(--yk-ink);
  text-decoration: none;
  transition: background 0.2s var(--yk-ease), color 0.2s var(--yk-ease);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  background: var(--yk-green);
  color: #ffffff;
  outline: none;
}

.page-about .about-rail__num {
  font-family: var(--yk-font-mono);
  font-size: 12px;
  color: var(--yk-orange-deep);
}

.page-about .about-rail__link:hover .about-rail__num,
.page-about .about-rail__link:focus-visible .about-rail__num {
  color: var(--yk-sand);
}

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

.page-about .about-content > section + section {
  margin-top: clamp(40px, 6.5vw, 80px);
}

.page-about .about-section__head {
  max-width: 62ch;
  margin-bottom: clamp(16px, 2.4vw, 24px);
}

.page-about .about-section__title {
  margin: 0 0 10px;
  font-family: var(--yk-font-display);
  font-size: clamp(23px, 3.3vw, 36px);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: -0.01em;
  color: var(--yk-ink);
}

.page-about .about-section__head p {
  margin: 0;
  color: var(--yk-rock);
  line-height: 1.8;
}

/* 缘起故事 */
.page-about .about-story {
  display: grid;
  gap: clamp(20px, 3.5vw, 36px);
  align-items: center;
}

.page-about .about-story__text p {
  margin: 0 0 1em;
  line-height: 1.9;
  color: var(--yk-ink);
}

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

.page-about .about-story__figure {
  margin: 0;
  border-radius: var(--yk-radius-lg);
  overflow: hidden;
  border: 1px solid var(--about-line);
  background: var(--yk-sand);
  box-shadow: var(--yk-shadow-soft);
}

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

.page-about .about-story__caption {
  padding: 12px 16px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--yk-rock);
  background: var(--yk-cream);
}

/* 维护方法：深色段 */
.page-about .about-method {
  padding: clamp(24px, 4.5vw, 52px);
  border-radius: var(--yk-radius-lg);
  background: var(--yk-green-deep);
  color: var(--yk-cream);
  box-shadow: var(--yk-shadow-lift);
}

.page-about .about-method .about-section__title {
  color: var(--yk-cream);
}

.page-about .about-method__top {
  display: grid;
  gap: 20px;
}

.page-about .about-method__intro p {
  margin: 0;
  color: rgba(250, 246, 236, 0.82);
  line-height: 1.85;
}

.page-about .about-method__figure {
  margin: 0;
  border-radius: var(--yk-radius-md);
  overflow: hidden;
  background: rgba(250, 246, 236, 0.08);
}

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

.page-about .about-steps {
  list-style: none;
  margin: clamp(20px, 3vw, 32px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-step {
  padding: 18px;
  border-radius: var(--yk-radius-md);
  border: 1px solid rgba(250, 246, 236, 0.2);
  background: rgba(250, 246, 236, 0.07);
  transition: transform 0.22s var(--yk-ease), background 0.22s var(--yk-ease), border-color 0.22s var(--yk-ease);
}

.page-about .about-step:hover,
.page-about .about-step:focus-within {
  transform: translateY(-3px);
  background: rgba(250, 246, 236, 0.14);
  border-color: var(--yk-moss);
}

.page-about .about-step__num {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--yk-orange);
}

.page-about .about-step__title {
  margin: 6px 0 8px;
  font-size: 18px;
  font-weight: 700;
  color: var(--yk-cream);
}

.page-about .about-step__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: rgba(250, 246, 236, 0.8);
}

.page-about .about-step__checks {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: grid;
  gap: 6px;
}

.page-about .about-step__checks li {
  position: relative;
  padding-left: 16px;
  font-size: 13px;
  line-height: 1.7;
  color: rgba(203, 231, 244, 0.9);
}

.page-about .about-step__checks li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--yk-moss);
}

.page-about .about-cadence {
  display: grid;
  gap: 12px;
  margin-top: clamp(20px, 3vw, 30px);
}

.page-about .about-cadence__item {
  padding-left: 14px;
  border-left: 3px solid var(--yk-sky-soft);
}

.page-about .about-cadence__title {
  margin: 0 0 4px;
  font-family: var(--yk-font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--yk-sky-soft);
}

.page-about .about-cadence__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: rgba(250, 246, 236, 0.78);
}

/* 版本历程 */
.page-about .about-milestones {
  padding: clamp(22px, 4.5vw, 48px);
  border-radius: var(--yk-radius-lg);
  background: var(--yk-sand);
}

.page-about .about-milestones__lead {
  margin: 0;
  max-width: 60ch;
  color: #4d4433;
  line-height: 1.85;
}

.page-about .about-milestones__figure {
  margin: clamp(16px, 2.6vw, 24px) 0 0;
  border-radius: var(--yk-radius-md);
  overflow: hidden;
  border: 1px solid rgba(181, 71, 31, 0.18);
}

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

.page-about .about-timeline {
  position: relative;
  list-style: none;
  margin: clamp(18px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 25px;
  top: 10px;
  bottom: 10px;
  width: 3px;
  border-radius: 3px;
  background: linear-gradient(180deg, var(--yk-green), var(--yk-sky) 55%, var(--yk-orange));
  opacity: 0.7;
}

.page-about .about-timeline__item {
  position: relative;
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 12px;
  align-items: start;
}

.page-about .about-timeline__badge {
  position: relative;
  z-index: 1;
  display: block;
  padding: 7px 2px;
  text-align: center;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--yk-green-deep);
  background: var(--yk-cream);
  border: 2px solid var(--yk-green);
  border-radius: var(--yk-radius-pill);
}

.page-about .about-timeline__card {
  padding: 14px 16px;
  border-radius: var(--yk-radius-md);
  background: var(--yk-cream);
  border: 1px solid rgba(21, 38, 31, 0.1);
}

.page-about .about-timeline__title {
  margin: 0 0 6px;
  font-size: 16px;
  font-weight: 700;
  color: var(--yk-ink);
}

.page-about .about-timeline__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--yk-rock);
}

.page-about .about-timeline__item--current .about-timeline__badge {
  color: #ffffff;
  background: var(--yk-orange);
  border-color: var(--yk-orange-deep);
}

.page-about .about-timeline__item--current .about-timeline__card {
  border-color: var(--yk-orange);
  background: #fff9f2;
  box-shadow: var(--yk-shadow-soft);
}

/* 路标标准 */
.page-about .about-values {
  display: grid;
  gap: 14px;
  margin-top: clamp(16px, 2.6vw, 24px);
}

.page-about .about-value {
  padding: clamp(18px, 2.6vw, 28px);
  border-radius: var(--yk-radius-lg);
  border: 2px solid var(--yk-green);
  background: var(--yk-cream);
}

.page-about .about-value--moss {
  border-color: var(--yk-moss);
  background: #f4f7ef;
}

.page-about .about-value--sky {
  border-color: var(--yk-sky);
  background: var(--yk-sky-soft);
}

.page-about .about-value--clay {
  border-color: var(--yk-clay);
  background: #fbf1ec;
}

.page-about .about-value--orange {
  border-color: var(--yk-orange);
  background: #fff3e9;
}

.page-about .about-value__num {
  display: block;
  font-size: 28px;
  font-weight: 700;
  line-height: 1;
  color: var(--yk-orange-deep);
}

.page-about .about-value__title {
  margin: 10px 0 8px;
  font-size: 19px;
  font-weight: 800;
  color: var(--yk-ink);
}

.page-about .about-value__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: #3a473f;
}

/* 团队与协作 */
.page-about .about-team {
  padding-top: clamp(20px, 3.2vw, 32px);
  border-top: 3px dashed var(--yk-green);
}

.page-about .about-team__text p {
  margin: 0 0 1em;
  line-height: 1.9;
  color: var(--yk-ink);
}

.page-about .about-stats {
  display: grid;
  gap: 12px;
  margin-top: clamp(16px, 2.6vw, 24px);
}

.page-about .about-stat {
  padding: 16px;
  border-radius: var(--yk-radius-md);
  border: 1px solid var(--about-line);
  background: #ffffff;
}

.page-about .about-stat__num {
  display: block;
  font-size: clamp(26px, 3.6vw, 34px);
  font-weight: 700;
  line-height: 1.1;
  color: var(--yk-green);
}

.page-about .about-stat__label {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--yk-rock);
}

.page-about .about-team__honor {
  margin: clamp(16px, 2.6vw, 22px) 0 0;
  padding: 12px 16px;
  border-radius: var(--yk-radius-md);
  border-left: 4px solid var(--yk-clay);
  background: var(--yk-sand);
  font-size: 14px;
  line-height: 1.75;
  color: #4d4433;
}

/* 下一步路标 */
.page-about .about-next {
  margin-top: clamp(36px, 6vw, 68px);
  padding: clamp(24px, 4vw, 44px);
  border-radius: var(--yk-radius-lg);
  background: var(--yk-green-deep);
  color: var(--yk-cream);
}

.page-about .about-next__title {
  margin: 0 0 10px;
  font-family: var(--yk-font-display);
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 800;
  color: var(--yk-cream);
}

.page-about .about-next__text {
  margin: 0;
  max-width: 62ch;
  line-height: 1.85;
  color: rgba(250, 246, 236, 0.82);
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.page-about .about-next .yk-btn--ghost {
  color: var(--yk-cream);
  border-color: rgba(250, 246, 236, 0.5);
}

.page-about .about-next .yk-btn--ghost:hover,
.page-about .about-next .yk-btn--ghost:focus-visible {
  border-color: var(--yk-sky-soft);
  color: var(--yk-sky-soft);
}

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

  .page-about .about-values {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

@media (min-width: 780px) {
  .page-about .about-story {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.85fr);
  }

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

  .page-about .about-method__top {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: center;
  }
}

@media (min-width: 920px) {
  .page-about .about-split {
    grid-template-columns: 232px minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 96px;
  }

  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-step,
  .page-about .about-rail__link {
    transition: none;
  }

  .page-about .about-step:hover,
  .page-about .about-step:focus-within {
    transform: none;
  }
}
<<<END>>>