.page-about {
  --page-about-rail: 248px;
  --page-about-hero-pad: 72px;
}

.page-about__hero {
  position: relative;
  overflow: hidden;
  background: var(--bg-primary);
  color: var(--text-light);
  padding-top: 56px;
  padding-bottom: 84px;
}

.page-about__hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 6px;
  background: linear-gradient(90deg, var(--accent-orange) 0 32%, var(--accent-cyan) 32% 64%, rgba(0, 194, 209, 0) 64%);
  z-index: 2;
}

.page-about__hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 20px;
}

.page-about__hero-art {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.page-about__hero-art::before {
  content: "";
  position: absolute;
  top: -20%;
  right: -12%;
  width: 72%;
  height: 150%;
  background:
    linear-gradient(135deg, transparent 47%, rgba(0, 194, 209, 0.16) 48%, rgba(0, 194, 209, 0.16) 50%, transparent 51%),
    linear-gradient(135deg, transparent 54%, rgba(255, 107, 0, 0.12) 55%, rgba(255, 107, 0, 0.12) 57%, transparent 58%);
  transform: rotate(12deg);
}

.page-about__vertical-text {
  position: absolute;
  top: 16px;
  right: -6px;
  writing-mode: vertical-rl;
  text-transform: uppercase;
  font-family: var(--font-mono);
  font-size: clamp(32px, 6vw, 72px);
  letter-spacing: 0.28em;
  color: rgba(245, 247, 250, 0.07);
}

.page-about__chapter-mark {
  position: absolute;
  right: 8px;
  bottom: -28px;
  font-family: var(--font-display);
  font-size: clamp(110px, 20vw, 240px);
  line-height: 1;
  color: rgba(255, 107, 0, 0.1);
}

.page-about__kicker {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--accent-cyan);
}

.page-about__hero h1 {
  margin: 0 0 20px;
  font-family: var(--font-display);
  font-size: var(--size-display-xl);
  line-height: 1.1;
  font-weight: 700;
  color: #F5F7FA;
  max-width: 15em;
  text-wrap: balance;
}

.page-about__keyword {
  color: var(--accent-cyan);
  border-bottom: 3px solid var(--accent-orange);
}

.page-about__lead {
  max-width: 34em;
  margin: 0;
  font-size: 17px;
  line-height: 1.75;
  color: rgba(245, 247, 250, 0.85);
}

.page-about__hero-meta {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about__hero-meta li {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--accent-orange-light);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-pill);
  padding: 7px 14px;
  background: rgba(17, 38, 79, 0.6);
}

.page-about__meta-batch {
  color: #FFFFFF !important;
  background: var(--accent-orange) !important;
  border-color: var(--accent-orange) !important;
  font-weight: 700;
}

.page-about__fav {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-body);
  font-size: 13px;
  color: var(--text-light);
  background: transparent;
  border: 0;
  cursor: pointer;
  padding: 0;
}

.page-about__layout {
  max-width: var(--container-width);
  margin-inline: auto;
  padding: 56px 24px 80px;
  display: grid;
  gap: 40px;
  align-items: start;
  background: var(--bg-light);
}

.page-about__index-label {
  margin: 0 0 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-gray);
}

.page-about__index-list {
  list-style: none;
  margin: 0;
  padding: 4px 0 8px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about__index-list li {
  flex: 0 0 auto;
}

.page-about__index-list a {
  display: block;
  padding: 10px 16px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 13px;
  line-height: 1.4;
  color: var(--text-dark);
  text-decoration: none;
  white-space: nowrap;
  background: #FFFFFF;
  transition: background var(--transition-base), color var(--transition-base), border-color var(--transition-base);
}

.page-about__index-list a:hover {
  border-color: rgba(255, 107, 0, 0.4);
  color: var(--accent-orange);
}

.page-about__index-list a.is-active {
  background: var(--accent-orange);
  border-color: var(--accent-orange);
  color: #FFFFFF;
}

.page-about__index-cta,
.page-about__index-tip {
  display: none;
}

.page-about__content {
  min-width: 0;
}

.page-about__section {
  position: relative;
  scroll-margin-top: calc(var(--header-height) + 24px);
  margin-bottom: 72px;
  overflow: hidden;
}

.page-about__section-mark {
  position: absolute;
  top: -18px;
  right: -6px;
  font-family: var(--font-display);
  font-size: clamp(120px, 18vw, 200px);
  line-height: 1;
  color: rgba(16, 24, 43, 0.05);
  pointer-events: none;
  z-index: 0;
}

.page-about__section > *:not(.page-about__section-mark) {
  position: relative;
  z-index: 1;
}

.page-about__section-head {
  border-bottom: 1px solid var(--border-blue);
  padding-bottom: 12px;
  margin-bottom: 28px;
}

.page-about__section-head h2 {
  margin: 0;
  display: flex;
  align-items: baseline;
  gap: 6px;
}

.page-about__section-num {
  font-family: var(--font-mono);
  font-size: var(--size-section-title);
  color: var(--accent-cyan);
  line-height: 1.1;
  font-weight: 700;
}

.page-about__section-slash {
  font-family: var(--font-mono);
  font-size: var(--size-section-title);
  color: var(--border-blue);
  line-height: 1.1;
}

.page-about__section-name {
  font-family: var(--font-display);
  font-size: var(--size-section-title);
  color: var(--text-dark);
  line-height: 1.15;
}

.page-about__section p {
  max-width: 62ch;
  margin: 0 0 18px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-dark);
}

.page-about__note {
  margin-top: 28px;
  background: #FFFFFF;
  border: 1px solid var(--border-light);
  border-left: 4px solid var(--accent-orange);
  border-radius: 0 12px 12px 0;
  padding: 22px 24px;
}

.page-about__note h3 {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-size: 20px;
  color: var(--text-dark);
  letter-spacing: 0.04em;
}

.page-about__note ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 10px;
}

.page-about__note li {
  padding-left: 18px;
  position: relative;
  font-size: 14px;
  line-height: 1.65;
  color: var(--text-gray);
}

.page-about__note li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 8px;
  height: 8px;
  transform: rotate(45deg);
  background: var(--accent-cyan);
}

.page-about__timeline-wrap {
  display: grid;
  gap: 32px;
  margin-top: 32px;
}

.page-about__timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  border-left: 2px solid var(--border-blue);
}

.page-about__timeline-item {
  position: relative;
  padding-left: 36px;
}

.page-about__timeline-item::before {
  content: "";
  position: absolute;
  left: -11px;
  top: 14px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-orange);
  border: 3px solid var(--bg-light);
  box-shadow: 0 0 0 2px var(--accent-orange);
}

.page-about__timeline-details {
  margin: 0;
}

.page-about__timeline-details summary {
  list-style: none;
  display: flex;
  align-items: baseline;
  gap: 18px;
  padding: 8px 0;
  cursor: pointer;
}

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

.page-about__timeline-details summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--accent-orange);
  transition: transform var(--transition-base);
}

.page-about__timeline-details[open] summary::after {
  content: "–";
}

.page-about__timeline-details summary:hover .page-about__timeline-title {
  color: var(--accent-orange);
}

.page-about__timeline-year {
  font-family: var(--font-mono);
  font-size: 36px;
  line-height: 1;
  color: var(--accent-orange);
  min-width: 70px;
  font-weight: 700;
}

.page-about__timeline-title {
  font-family: var(--font-display);
  font-size: 22px;
  line-height: 1.3;
  color: var(--text-dark);
  transition: color var(--transition-base);
}

.page-about__timeline-desc {
  margin: 12px 0 24px !important;
  padding: 14px 16px;
  background: #FFFFFF;
  border: 1px solid var(--border-light);
  border-left: 3px solid var(--accent-cyan);
  border-radius: 0 10px 10px 0;
  font-size: 13px !important;
  line-height: 1.7 !important;
  color: var(--text-gray) !important;
}

.page-about__figure {
  margin: 8px 0 0;
}

.page-about__figure img,
.page-about__figure > img {
  width: 100%;
  height: auto;
  display: block;
  border-radius: var(--radius-card);
  background: var(--bg-secondary);
  object-fit: cover;
}

.page-about__figure figcaption {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--text-gray);
  letter-spacing: 0.04em;
}

.page-about__stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin: 36px 0 32px;
}

.page-about__stat {
  position: relative;
  overflow: hidden;
  background: var(--bg-primary);
  color: var(--text-light);
  padding: 22px 20px;
  border-radius: var(--radius-card);
}

.page-about__stat::after {
  content: "";
  position: absolute;
  right: -18px;
  bottom: -18px;
  width: 60px;
  height: 60px;
  background: rgba(255, 107, 0, 0.18);
  clip-path: polygon(0% 0%, 100% 100%, 0% 100%);
}

.page-about__stat-value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(30px, 5vw, 46px);
  line-height: 1.1;
  color: var(--accent-cyan);
  font-weight: 700;
}

.page-about__stat-unit {
  color: var(--accent-orange);
  font-size: 0.7em;
}

.page-about__stat-label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.5;
  color: rgba(245, 247, 250, 0.72);
}

.page-about__chart {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 720 / 280;
  margin: 32px 0 12px;
  background: #FFFFFF;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-card);
  padding: 16px 12px;
  box-shadow: 0 8px 24px rgba(11, 27, 61, 0.08);
}

.page-about__chart text {
  font-family: var(--font-mono);
  font-size: 20px;
  fill: var(--text-gray);
}

.page-about__chart .page-about__chart-total {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  fill: var(--accent-orange);
}

.page-about__chart-note {
  margin: 0 0 24px !important;
  font-size: 13px !important;
  line-height: 1.7 !important;
  color: var(--text-gray) !important;
}

.page-about__update-grid {
  display: grid;
  gap: 16px;
  margin: 32px 0;
}

.page-about__update-card {
  position: relative;
  overflow: hidden;
  background: var(--bg-secondary);
  color: var(--text-light);
  padding: 24px;
  border-radius: var(--radius-card);
}

.page-about__update-card::after {
  content: "";
  position: absolute;
  right: -14px;
  top: -14px;
  width: 48px;
  height: 48px;
  background: rgba(0, 194, 209, 0.25);
  clip-path: polygon(0% 0%, 100% 100%, 0% 100%);
}

.page-about__update-card h3 {
  margin: 0 0 10px;
  font-size: 15px;
  line-height: 1.4;
  color: var(--accent-cyan);
}

.page-about__update-card p {
  margin: 0;
  font-size: 13px !important;
  line-height: 1.7 !important;
  color: rgba(245, 247, 250, 0.76) !important;
}

.page-about__promise-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  counter-reset: promise;
  display: grid;
  gap: 14px;
}

.page-about__promise-list li {
  counter-increment: promise;
  position: relative;
  background: #FFFFFF;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-card);
  padding: 18px 20px 18px 52px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--text-dark);
}

.page-about__promise-list li::before {
  content: counter(promise, decimal-leading-zero);
  position: absolute;
  left: 16px;
  top: 17px;
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: 700;
  color: var(--accent-orange);
}

.page-about__promise-box {
  position: relative;
  overflow: hidden;
  margin-top: 40px;
  padding: 32px;
  border-radius: 16px;
  background: var(--bg-primary);
  color: var(--text-light);
}

.page-about__promise-box::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--accent-orange), var(--accent-cyan));
}

.page-about__promise-box h3 {
  margin: 0 0 22px;
  font-family: var(--font-display);
  font-size: 26px;
  line-height: 1.3;
  color: var(--text-light);
}

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

.page-about__contact-list li {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: 14px;
  line-height: 1.6;
}

.page-about__contact-list .label {
  min-width: 88px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: rgba(245, 247, 250, 0.56);
  text-transform: uppercase;
}

.page-about__contact-list .value {
  color: var(--text-light);
  word-break: break-all;
}

.page-about__contact-note {
  margin: 18px 0 0 !important;
  font-size: 13px !important;
  line-height: 1.7 !important;
  color: rgba(245, 247, 250, 0.6) !important;
}

.page-about__promise-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 22px;
  padding-top: 20px;
  border-top: 1px solid rgba(141, 155, 181, 0.25);
}

.page-about__promise-links a {
  font-size: 13px;
  color: var(--accent-cyan);
  text-decoration: none;
  border: 1px solid rgba(0, 194, 209, 0.4);
  border-radius: var(--radius-pill);
  padding: 8px 16px;
  transition: background var(--transition-base), color var(--transition-base);
}

.page-about__promise-links a:hover {
  background: rgba(0, 194, 209, 0.12);
  color: var(--text-light);
}

.page-about__next {
  background: var(--bg-primary);
  color: var(--text-light);
  border-radius: 20px;
  padding: 32px;
  margin-top: 64px;
}

.page-about__next-head {
  display: block;
  margin-bottom: 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--accent-cyan);
}

.page-about__next-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.page-about__next-nav a {
  display: inline-block;
  padding: 9px 16px;
  border-radius: var(--radius-pill);
  background: transparent;
  border: 1px solid rgba(255, 154, 77, 0.42);
  color: var(--accent-orange-light);
  font-size: 14px;
  line-height: 1.5;
  text-decoration: none;
  transition: background var(--transition-base), color var(--transition-base);
}

.page-about__next-nav a:hover {
  background: var(--accent-orange);
  border-color: var(--accent-orange);
  color: #FFFFFF;
}

@media (min-width: 640px) {
  .page-about__contact-list li {
    flex-direction: row;
    gap: 16px;
    align-items: baseline;
  }

  .page-about__stats {
    grid-template-columns: repeat(4, 1fr);
  }

  .page-about__update-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .page-about__lead {
    font-size: 18px;
  }
}

@media (min-width: 760px) {
  .page-about__hero {
    padding-top: var(--page-about-hero-pad);
    padding-bottom: 112px;
  }

  .page-about__promise-box {
    padding: 40px;
  }

  .page-about__next {
    padding: 40px;
  }
}

@media (min-width: 980px) {
  .page-about__layout {
    grid-template-columns: var(--page-about-rail) minmax(0, 1fr);
    gap: 64px;
    padding-top: 72px;
  }

  .page-about__index {
    position: sticky;
    top: calc(var(--header-height) + 24px);
    align-self: start;
  }

  .page-about__index-list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about__index-list li {
    flex: none;
  }

  .page-about__index-list a {
    margin-bottom: 6px;
    background: transparent;
    border-radius: 999px;
  }

  .page-about__index-list a:hover {
    background: rgba(255, 107, 0, 0.08);
  }

  .page-about__index-list a.is-active {
    background: var(--accent-orange);
    color: #FFFFFF;
  }

  .page-about__index-cta,
  .page-about__index-tip {
    display: block;
  }

  .page-about__index-cta {
    margin-top: 24px;
    width: 100%;
    justify-content: center;
  }

  .page-about__index-tip {
    margin: 16px 0 0;
    font-size: 12px;
    line-height: 1.7;
    color: var(--text-gray);
  }

  .page-about__timeline-wrap {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: start;
    gap: 48px;
  }

  .page-about__section > p {
    font-size: 16px;
  }

  .page-about__hero h1 {
    max-width: 13em;
  }

  .page-about__stat {
    padding: 26px 22px;
  }
}