.page-about {
  background: var(--color-bg);
  color: var(--color-cream);
  overflow-x: hidden;
}

.page-about .about-shell {
  width: 100%;
  max-width: var(--shell-w);
  margin: 0 auto;
  padding: 0 clamp(16px, 4vw, 48px);
}

.page-about .about-index {
  display: block;
  position: relative;
  padding: 16px 0 0;
  z-index: 2;
}

.page-about .index-script {
  display: none;
}

.page-about .index-title {
  display: none;
}

.page-about .index-list {
  list-style: none;
  display: flex;
  gap: 6px;
  margin: 0;
  padding: 6px 0 2px;
  overflow-x: auto;
}

.page-about .index-item {
  flex: 0 0 auto;
}

.page-about .index-item a {
  display: block;
  padding: 8px 12px;
  font-size: 13px;
  color: var(--color-stone);
  text-decoration: none;
  background: rgba(26, 29, 36, 0.8);
  border: 1px solid rgba(168, 174, 184, 0.25);
  transition: color 0.2s ease, border-color 0.2s ease, background 0.2s ease;
}

.page-about .index-item a:hover,
.page-about .index-item a:focus-visible {
  color: var(--color-gold-bright);
  border-color: var(--color-gold);
}

.page-about .index-num {
  font-family: var(--font-num);
  margin-right: 6px;
  color: var(--color-gold);
}

.page-about .index-contact {
  display: none;
}

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

.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  padding: 18px 0 0;
  font-size: 13px;
  color: var(--color-stone);
}

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

.page-about .breadcrumb a:hover {
  color: var(--color-gold);
}

.page-about .breadcrumb-sep {
  color: rgba(231, 184, 76, 0.5);
}

.page-about .about-hero {
  position: relative;
  padding: 44px 0 48px;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: -24px;
  right: -10%;
  width: 62%;
  height: 130%;
  background:
    linear-gradient(135deg, rgba(231, 184, 76, 0.14) 0%, rgba(231, 184, 76, 0.02) 48%, transparent 60%),
    linear-gradient(45deg, transparent 55%, rgba(194, 58, 58, 0.18) 55%, rgba(194, 58, 58, 0.18) 62%, transparent 62%);
  clip-path: polygon(24% 0, 100% 0, 84% 100%, 0 100%);
  pointer-events: none;
  z-index: 0;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: 32px;
  right: 10%;
  width: 14px;
  height: 14px;
  background: var(--color-gold-bright);
  transform: rotate(45deg);
  box-shadow: 0 0 28px rgba(231, 184, 76, 0.9), 0 0 60px rgba(231, 184, 76, 0.35);
  z-index: 0;
}

.page-about .hero-seal {
  position: absolute;
  top: 40px;
  right: 12px;
  writing-mode: vertical-rl;
  font-family: var(--font-serif);
  font-size: 12px;
  letter-spacing: 0.4em;
  color: rgba(231, 184, 76, 0.72);
  border: 1px solid rgba(231, 184, 76, 0.35);
  padding: 10px 6px;
  z-index: 1;
  user-select: none;
  pointer-events: none;
}

.page-about .hero-kicker {
  position: relative;
  z-index: 1;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-gold);
  margin-bottom: 16px;
}

.page-about .hero-kicker::before {
  content: "";
  width: 26px;
  height: 1px;
  background: var(--color-red);
}

.page-about .about-hero .page-title {
  position: relative;
  z-index: 1;
  max-width: 13em;
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 4.5vw, 3.4rem);
  font-weight: 900;
  line-height: 1.25;
  letter-spacing: 0.02em;
  color: var(--color-cream);
}

.page-about .about-hero .page-intro {
  position: relative;
  z-index: 1;
  margin-top: 18px;
  max-width: 42em;
  color: var(--color-stone);
  font-size: 16px;
  line-height: 1.75;
}

.page-about .section-block {
  position: relative;
  padding-bottom: 48px;
  margin-bottom: 40px;
}

.page-about .section-block::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -12px;
  width: 100%;
  height: 1px;
  background: linear-gradient(90deg, rgba(231, 184, 76, 0.5) 0%, rgba(231, 184, 76, 0.08) 30%, transparent 100%);
}

.page-about .commit-section::after {
  display: none;
}

.page-about .section-heading {
  margin-bottom: 18px;
}

.page-about .section-kicker {
  display: inline-block;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--color-gold);
  margin-bottom: 8px;
}

.page-about .section-kicker::before {
  content: "";
  display: inline-block;
  width: 20px;
  height: 1px;
  background: var(--color-red);
  vertical-align: middle;
  margin-right: 8px;
}

.page-about .section-heading h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.5rem, 3vw, 2.2rem);
  font-weight: 800;
  line-height: 1.3;
  color: var(--color-cream);
  margin: 0;
}

.page-about .brand-story {
  display: grid;
  grid-template-areas: "copy" "visual";
  gap: 24px;
}

.page-about .story-copy {
  grid-area: copy;
}

.page-about .story-visual {
  grid-area: visual;
}

.page-about .story-copy p {
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-stone);
  margin: 0 0 16px;
}

.page-about .story-copy .btn {
  margin-top: 8px;
}

.page-about .story-visual,
.page-about .milestone-visual,
.page-about .system-chart {
  position: relative;
  overflow: hidden;
  background: var(--color-bg-secondary);
}

.page-about .story-visual img,
.page-about .milestone-visual img,
.page-about .system-chart img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
}

.page-about .milestone-section {
  display: grid;
  grid-template-areas: "content" "visual";
  gap: 32px;
}

.page-about .milestone-content {
  position: relative;
  grid-area: content;
  min-width: 0;
}

.page-about .milestone-content::before {
  content: "V1 — V4";
  position: absolute;
  right: 4px;
  top: -8px;
  font-family: var(--font-num);
  font-size: clamp(4rem, 8vw, 7rem);
  font-weight: 800;
  color: rgba(231, 184, 76, 0.06);
  line-height: 1;
  pointer-events: none;
  z-index: 0;
  white-space: nowrap;
}

.page-about .milestone-content .section-heading,
.page-about .milestone-intro,
.page-about .timeline,
.page-about .milestone-content .btn {
  position: relative;
  z-index: 1;
}

.page-about .milestone-visual {
  grid-area: visual;
}

.page-about .milestone-visual img {
  width: 100%;
  max-height: 400px;
  object-fit: cover;
  object-position: center 15%;
}

.page-about .milestone-intro {
  color: var(--color-stone);
  line-height: 1.75;
  margin: 0 0 24px;
}

.page-about .timeline {
  position: relative;
  padding-left: 36px;
  margin-bottom: 20px;
}

.page-about .timeline-rail {
  position: absolute;
  left: 10px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  height: auto;
  color: var(--color-gold);
  opacity: 0.45;
  overflow: visible;
}

.page-about .timeline-item {
  position: relative;
  display: block;
  margin-bottom: 16px;
}

.page-about .timeline-summary {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
  list-style: none;
  cursor: pointer;
  padding: 18px 20px 18px 26px;
  background: linear-gradient(135deg, rgba(26, 29, 36, 0.98) 0%, rgba(22, 25, 31, 0.98) 100%);
  clip-path: polygon(0 0, calc(100% - 14px) 0, 100% 100%, 0 100%);
  border-left: 3px solid var(--color-gold);
  transition: background 0.2s ease, border-left-color 0.2s ease, transform 0.2s ease;
}

.page-about .timeline-summary::-webkit-details-marker {
  content: "";
  display: none;
}

.page-about .timeline-summary::marker {
  content: "";
}

.page-about .timeline-summary:hover {
  background: rgba(35, 39, 48, 0.98);
  border-left-color: var(--color-gold-bright);
}

.page-about .timeline-summary:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 2px;
}

.page-about .timeline-item[open] .timeline-summary {
  border-left-color: var(--color-red);
  background: linear-gradient(135deg, rgba(194, 58, 58, 0.14) 0%, rgba(26, 29, 36, 0.98) 30%);
}

.page-about .timeline-dot {
  position: absolute;
  left: -36px;
  top: 50%;
  width: 9px;
  height: 9px;
  background: var(--color-gold);
  transform: rotate(45deg) translateY(-50%);
  box-shadow: 0 0 12px rgba(231, 184, 76, 0.8);
}

.page-about .timeline-version {
  font-family: var(--font-serif);
  font-size: 1.9rem;
  font-weight: 900;
  line-height: 1;
  color: var(--color-gold);
  letter-spacing: 0.02em;
}

.page-about .timeline-heading {
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 600;
  color: var(--color-cream);
}

.page-about .timeline-body {
  padding: 12px 12px 4px 26px;
  color: var(--color-stone);
  font-size: 14px;
  line-height: 1.75;
}

.page-about .timeline-body p {
  margin: 0 0 10px;
}

.page-about .system-intro {
  max-width: 52em;
  color: var(--color-stone);
  line-height: 1.75;
  margin: 0 0 24px;
}

.page-about .system-chart {
  margin-bottom: 32px;
}

.page-about .system-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

.page-about .system-card {
  position: relative;
  padding: 22px 20px 20px;
  background: var(--color-bg-secondary);
  border-top: 2px solid transparent;
  transition: border-color 0.2s ease, background 0.2s ease;
}

.page-about .system-card:hover {
  border-top-color: var(--color-gold);
  background: rgba(30, 34, 42, 0.9);
}

.page-about .system-card-title {
  font-family: var(--font-serif);
  font-size: 17px;
  font-weight: 700;
  color: var(--color-cream);
  margin: 0 0 8px;
}

.page-about .system-card p {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-stone);
  margin: 0 0 14px;
}

.page-about .link-arrow {
  display: inline-block;
  font-size: 13px;
  color: var(--color-teal);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease;
}

.page-about .link-arrow:hover {
  border-bottom-color: var(--color-teal);
}

.page-about .key-matrix {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  margin-top: 36px;
  border-top: 1px solid rgba(231, 184, 76, 0.35);
  border-left: 1px solid rgba(231, 184, 76, 0.35);
}

.page-about .matrix-cell {
  display: block;
  padding: 18px 16px;
  border-right: 1px solid rgba(231, 184, 76, 0.35);
  border-bottom: 1px solid rgba(231, 184, 76, 0.35);
  text-decoration: none;
  background: transparent;
  transition: background 0.2s ease, box-shadow 0.2s ease;
}

.page-about .matrix-cell:hover {
  background: rgba(231, 184, 76, 0.09);
  box-shadow: inset 4px 0 0 var(--color-gold);
}

.page-about .matrix-cell:focus-visible {
  background: rgba(231, 184, 76, 0.09);
  box-shadow: inset 0 0 0 2px var(--color-gold);
  outline: 2px solid var(--color-gold-bright);
  outline-offset: 2px;
}

.page-about .matrix-num {
  font-family: var(--font-num);
  font-size: 2.2rem;
  font-weight: 700;
  line-height: 1;
  color: var(--color-gold-bright);
}

.page-about .matrix-label {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--color-stone);
  text-transform: uppercase;
}

.page-about .commit-section {
  position: relative;
  padding: 40px 24px 32px;
  background: linear-gradient(180deg, rgba(194, 58, 58, 0.05) 0%, rgba(26, 29, 36, 0.82) 30%);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 28px), 0 100%);
  margin-bottom: 48px;
}

.page-about .commit-section::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--color-red) 0%, var(--color-gold) 100%);
}

.page-about .commit-ribbon {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--color-red) 0%, var(--color-gold) 100%);
  z-index: 1;
}

.page-about .commit-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-top: 24px;
}

.page-about .commit-card {
  padding: 22px 20px;
  background: rgba(26, 29, 36, 0.76);
  border-left: 2px solid var(--color-gold);
  transition: transform 0.2s ease, background 0.2s ease;
}

.page-about .commit-card:hover {
  background: rgba(34, 38, 48, 0.9);
  transform: translateY(-2px);
}

.page-about .commit-card-title {
  font-family: var(--font-serif);
  font-size: 16px;
  font-weight: 700;
  margin: 0 0 8px;
  color: var(--color-cream);
}

.page-about .commit-card p {
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-stone);
  margin: 0;
}

.page-about .contact-strip {
  display: grid;
  grid-template-columns: 1fr;
  margin-top: 28px;
  border-top: 1px solid rgba(231, 184, 76, 0.3);
}

.page-about .contact-item {
  padding: 14px 4px;
  border-bottom: 1px solid rgba(231, 184, 76, 0.12);
}

.page-about .contact-label {
  display: block;
  font-family: var(--font-num);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-gold);
  margin-bottom: 4px;
}

.page-about .contact-text {
  font-size: 14px;
  line-height: 1.5;
  color: var(--color-cream);
}

.page-about .commit-footer {
  display: flex;
  flex-direction: column;
  gap: 16px;
  align-items: flex-start;
  margin-top: 28px;
  padding: 20px 0 0;
}

.page-about .commit-footer p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-stone);
}

.page-about .v-note {
  font-family: var(--font-num);
  font-size: 11px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--color-stone);
}

.page-about a:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 3px;
}

@media (min-width: 720px) {
  .page-about .system-grid {
    grid-template-columns: 1fr 1fr;
    gap: 20px;
  }

  .page-about .commit-grid {
    grid-template-columns: 1fr 1fr;
    gap: 20px;
  }

  .page-about .contact-strip {
    grid-template-columns: 1fr 1fr;
  }

  .page-about .contact-item:nth-child(even) {
    padding-left: 14px;
  }

  .page-about .commit-footer {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }

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

  .page-about .milestone-visual img {
    max-height: 560px;
  }
}

@media (min-width: 960px) {
  .page-about .about-shell {
    display: grid;
    grid-template-columns: 220px minmax(0, 1fr);
    gap: clamp(32px, 5vw, 80px);
    padding-top: 24px;
  }

  .page-about .about-index {
    position: sticky;
    top: calc(var(--header-h) + 24px);
    align-self: start;
    padding-top: 72px;
  }

  .page-about .index-script {
    display: block;
    font-family: var(--font-num);
    font-size: 12px;
    letter-spacing: 0.28em;
    text-transform: uppercase;
    color: var(--color-stone);
    margin-bottom: 8px;
  }

  .page-about .index-title {
    display: block;
    font-family: var(--font-serif);
    font-size: 18px;
    font-weight: 700;
    color: var(--color-cream);
    margin: 0 0 14px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--color-gold);
  }

  .page-about .index-list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding: 0;
  }

  .page-about .index-item a {
    border: 0;
    border-bottom: 1px solid rgba(168, 174, 184, 0.18);
    background: transparent;
    padding: 11px 0;
    font-size: 14px;
  }

  .page-about .index-contact {
    display: block;
    margin-top: 40px;
    padding: 14px 16px;
    background: rgba(26, 29, 36, 0.85);
    border-left: 2px solid var(--color-gold);
  }

  .page-about .index-contact-label {
    display: block;
    font-family: var(--font-num);
    font-size: 11px;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--color-gold);
    margin-bottom: 4px;
  }

  .page-about .index-contact-value {
    display: block;
    font-size: 15px;
    color: var(--color-cream);
  }

  .page-about .index-contact-note {
    display: block;
    margin-top: 6px;
    font-size: 12px;
    color: var(--color-stone);
  }

  .page-about .about-hero {
    padding: 64px 0 72px;
  }

  .page-about .hero-seal {
    right: 8%;
  }

  .page-about .section-block {
    padding-bottom: 72px;
    margin-bottom: 64px;
  }

  .page-about .brand-story {
    grid-template-columns: minmax(0, 1.15fr) minmax(260px, 0.85fr);
    grid-template-areas: "copy visual";
    gap: 48px;
    align-items: center;
  }

  .page-about .milestone-section {
    grid-template-columns: minmax(260px, 0.75fr) minmax(0, 1.25fr);
    grid-template-areas: "visual content";
    gap: 56px;
    align-items: start;
  }

  .page-about .milestone-visual img {
    max-height: 680px;
    object-position: center 20%;
  }

  .page-about .system-chart {
    margin-bottom: 40px;
  }

  .page-about .commit-section {
    padding: 48px 40px 40px;
  }

  .page-about .contact-strip {
    grid-template-columns: repeat(5, 1fr);
  }

  .page-about .contact-item {
    padding-right: 16px;
  }

  .page-about .contact-item:not(:last-child) {
    border-right: 1px solid rgba(231, 184, 76, 0.12);
  }
}

@media (min-width: 1100px) {
  .page-about .contact-strip {
    grid-template-columns: repeat(5, 1fr);
  }

  .page-about .contact-item:nth-child(even) {
    padding-left: 0;
  }

  .page-about .contact-item:not(:last-child) {
    border-right: 1px solid rgba(231, 184, 76, 0.12);
    padding-right: 16px;
  }
}