.page-about {
  --about-narrow: 35rem;
  --about-rule: rgba(143, 169, 158, .22);
  background:
    radial-gradient(120% 70% at 92% -12%, rgba(46, 211, 198, .10), transparent 62%),
    radial-gradient(90% 55% at 2% 8%, rgba(255, 107, 74, .08), transparent 58%),
    var(--sea-900);
  color: var(--fog);
  font-family: var(--ff-body);
  overflow-x: clip;
}

.page-about a {
  color: var(--sand);
  text-decoration: none;
  border-bottom: 1px solid rgba(230, 181, 102, .38);
  transition: color .2s var(--ease), border-color .2s var(--ease);
}

.page-about a:hover,
.page-about a:focus-visible {
  color: var(--coral);
  border-bottom-color: var(--coral);
}

.page-about .crumbs {
  margin-bottom: clamp(1.5rem, 4vw, 2.5rem);
}

/* ---------- hero ---------- */

.page-about .about-hero {
  position: relative;
  padding-top: clamp(1.5rem, 4vw, 2.5rem);
  padding-bottom: clamp(2.25rem, 5.5vw, 4rem);
  isolation: isolate;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(230, 181, 102, .55) 22%, rgba(46, 211, 198, .45) 78%, transparent);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -18%;
  right: -14%;
  width: min(46vw, 480px);
  aspect-ratio: 1;
  border: 1px solid rgba(143, 169, 158, .16);
  border-radius: 50%;
  box-shadow: 0 0 0 40px rgba(143, 169, 158, .04), 0 0 0 90px rgba(143, 169, 158, .025);
  transform: rotate(-16deg);
  pointer-events: none;
  z-index: -1;
}

.page-about .about-hero-grid {
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
}

.page-about .about-kicker {
  margin: 0 0 1rem;
  font-size: var(--fs-12);
  letter-spacing: .18em;
  color: var(--sand);
  text-transform: uppercase;
}

.page-about h1 {
  margin: 0 0 1.25rem;
  font-family: var(--ff-head);
  font-size: var(--fs-48);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.03em;
  color: var(--fog);
  max-width: 18ch;
}

.page-about .about-lede {
  margin: 0;
  max-width: var(--about-narrow);
  font-size: var(--fs-16);
  line-height: 1.85;
  color: rgba(234, 242, 240, .84);
}

.page-about .about-hero-side {
  align-self: end;
  padding: 1.25rem 1.35rem;
  background: rgba(12, 42, 64, .72);
  border: 1px solid var(--about-rule);
  clip-path: polygon(0 0, calc(100% - var(--cut)) 0, 100% var(--cut), 100% 100%, var(--cut) 100%, 0 calc(100% - var(--cut)));
}

.page-about .about-side-label {
  margin: 0 0 .85rem;
  font-size: var(--fs-12);
  letter-spacing: .22em;
  color: var(--mist);
}

.page-about .about-quick {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .1rem;
}

.page-about .about-quick li {
  display: flex;
  align-items: baseline;
  gap: .75rem;
  padding: .6rem 0;
  border-bottom: 1px solid rgba(143, 169, 158, .14);
}

.page-about .about-quick li:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .about-quick b {
  font-weight: 500;
  font-size: 1.15rem;
  color: var(--sand);
  min-width: 3.4rem;
}

.page-about .about-quick span {
  font-size: var(--fs-14);
  color: var(--mist);
}

/* ---------- chapter shell ---------- */

.page-about .about-track {
  padding-bottom: clamp(3rem, 7vw, 6rem);
}

.page-about .about-chapter {
  display: grid;
  gap: 1.5rem;
  padding-block: clamp(2.25rem, 5vw, 4rem);
  border-bottom: 1px solid var(--about-rule);
  background-image: linear-gradient(114deg, rgba(46, 211, 198, .05), transparent 30%);
}

.page-about .about-chapter:last-of-type {
  border-bottom: 0;
}

.page-about .about-rail {
  display: flex;
  align-items: center;
  gap: .9rem;
}

.page-about .about-index {
  display: block;
  font-family: var(--ff-mono);
  font-size: clamp(2.4rem, 8vw, 4.25rem);
  font-weight: 500;
  line-height: .82;
  letter-spacing: -0.04em;
  color: transparent;
  -webkit-text-stroke: 1.4px rgba(230, 181, 102, .58);
  user-select: none;
}

.page-about .about-rot {
  writing-mode: horizontal-tb;
  font-family: var(--ff-mono);
  font-size: .6875rem;
  letter-spacing: .2em;
  color: var(--mist);
  white-space: nowrap;
}

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

.page-about .about-body h2 {
  margin: 0 0 1rem;
  font-family: var(--ff-head);
  font-size: var(--fs-28);
  font-weight: 800;
  line-height: 1.24;
  letter-spacing: -0.02em;
  color: var(--fog);
}

.page-about .about-body h3 {
  margin: 0 0 .4rem;
  font-family: var(--ff-head);
  font-size: var(--fs-20);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--fog);
}

.page-about .about-body p {
  margin: 0 0 1rem;
  max-width: var(--about-narrow);
  font-size: var(--fs-16);
  line-height: 1.85;
  color: rgba(234, 242, 240, .82);
}

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

.page-about .about-inline-links {
  margin-top: 1.5rem;
  padding-top: 1.1rem;
  border-top: 1px dashed rgba(143, 169, 158, .28);
}

/* ---------- figure ---------- */

.page-about .about-figure {
  margin: 1.75rem 0 0;
  max-width: 44rem;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--about-rule);
  clip-path: polygon(0 0, calc(100% - var(--cut)) 0, 100% var(--cut), 100% 100%, 0 100%);
  background: var(--sea-800);
}

.page-about .about-figure figcaption {
  margin-top: .7rem;
  font-size: var(--fs-12);
  line-height: 1.7;
  color: var(--mist);
  max-width: 34rem;
}

/* ---------- timeline ---------- */

.page-about .tl-wrap {
  margin: 1.5rem 0 0;
}

.page-about .tl-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .tl-item {
  border-left: 1px solid rgba(46, 211, 198, .28);
  padding-left: 1.1rem;
  transition: border-color .25s var(--ease);
}

.page-about .tl-item[open] {
  border-left-color: var(--teal);
}

.page-about .tl-item > summary {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: .8rem;
  padding: .9rem 0;
  cursor: pointer;
  list-style: none;
}

.page-about .tl-item > summary::-webkit-details-marker {
  display: none;
}

.page-about .tl-item > summary:focus-visible {
  outline: 2px solid var(--coral);
  outline-offset: 3px;
}

.page-about .tl-year {
  font-size: var(--fs-14);
  color: var(--sand);
  letter-spacing: .04em;
  white-space: nowrap;
}

.page-about .tl-title {
  font-size: var(--fs-16);
  font-weight: 600;
  color: var(--fog);
  line-height: 1.5;
}

.page-about .tl-mark {
  position: relative;
  width: 1.15rem;
  height: 1.15rem;
  border: 1px solid rgba(46, 211, 198, .7);
  border-radius: 50%;
  color: var(--teal);
  flex: none;
}

.page-about .tl-mark::before,
.page-about .tl-mark::after {
  content: "";
  position: absolute;
  background: currentColor;
  transition: opacity .2s var(--ease), transform .3s var(--ease);
}

.page-about .tl-mark::before {
  left: 24%;
  right: 24%;
  top: calc(50% - .5px);
  height: 1px;
}

.page-about .tl-mark::after {
  top: 24%;
  bottom: 24%;
  left: calc(50% - .5px);
  width: 1px;
}

.page-about .tl-item[open] .tl-mark::after {
  opacity: 0;
  transform: scaleY(.4);
}

.page-about .tl-body {
  padding: 0 0 1.1rem;
}

.page-about .tl-body p {
  margin: 0;
  max-width: 33rem;
  font-size: var(--fs-14);
  line-height: 1.85;
  color: var(--mist);
}

/* ---------- team ---------- */

.page-about .team-list {
  display: grid;
  gap: 1.35rem;
  margin: 1.5rem 0 1.75rem;
}

.page-about .team-row {
  padding-bottom: 1.15rem;
  border-bottom: 1px solid rgba(143, 169, 158, .16);
}

.page-about .team-row:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .team-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: .55rem;
}

.page-about .team-name {
  font-family: var(--ff-head);
  font-size: var(--fs-20);
  font-weight: 700;
  color: var(--fog);
}

.page-about .team-count {
  font-size: var(--fs-14);
  color: var(--sand);
}

.page-about .team-bar {
  height: 4px;
  border-radius: 2px;
  background: rgba(143, 169, 158, .16);
  overflow: hidden;
  margin-bottom: .7rem;
}

.page-about .team-bar > span {
  display: block;
  width: var(--w, 30%);
  height: 100%;
  background: linear-gradient(90deg, var(--teal), var(--sand));
  border-radius: 2px;
}

.page-about .team-desc {
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.85;
  color: rgba(234, 242, 240, .76);
  max-width: 34rem;
}

/* ---------- flow ---------- */

.page-about .flow-list {
  list-style: none;
  margin: 1.5rem 0 1.5rem;
  padding: 0;
  display: grid;
  gap: 1.15rem;
}

.page-about .flow-step {
  display: grid;
  grid-template-columns: 2.4rem minmax(0, 1fr);
  gap: .9rem;
  padding: 1rem 1.15rem 1rem 1rem;
  background: rgba(12, 42, 64, .6);
  border: 1px solid var(--about-rule);
  border-left: 2px solid rgba(46, 211, 198, .55);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 14px), calc(100% - 14px) 100%, 0 100%);
}

.page-about .flow-num {
  font-size: var(--fs-14);
  color: var(--teal);
  letter-spacing: .06em;
  padding-top: .2rem;
}

.page-about .flow-copy p {
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.85;
  color: rgba(234, 242, 240, .78);
  max-width: 32rem;
}

/* ---------- cases ---------- */

.page-about .case-grid {
  display: grid;
  gap: 1rem;
  margin: 1.5rem 0 1.5rem;
}

.page-about .case-card {
  padding: 1.15rem 1.2rem 1.25rem;
  background: rgba(12, 42, 64, .62);
  border: 1px solid var(--about-rule);
  clip-path: polygon(var(--cut) 0, 100% 0, 100% calc(100% - var(--cut)), calc(100% - var(--cut)) 100%, 0 100%, 0 var(--cut));
}

.page-about .case-card .tag {
  display: inline-block;
  margin-bottom: .7rem;
  font-size: var(--fs-12);
  letter-spacing: .1em;
}

.page-about .case-card p {
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.85;
  color: rgba(234, 242, 240, .78);
  max-width: none;
}

/* ---------- contact ---------- */

.page-about .contact-card {
  margin: 1.5rem 0;
  padding: 1.25rem 1.3rem;
  background: linear-gradient(160deg, rgba(255, 107, 74, .10), rgba(12, 42, 64, .75) 55%);
  border: 1px solid rgba(255, 107, 74, .34);
  clip-path: polygon(0 0, calc(100% - var(--cut)) 0, 100% var(--cut), 100% 100%, var(--cut) 100%, 0 calc(100% - var(--cut)));
}

.page-about .contact-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .95rem;
}

.page-about .contact-list li {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: .5rem .9rem;
  padding-bottom: .85rem;
  border-bottom: 1px dashed rgba(143, 169, 158, .24);
}

.page-about .contact-list li:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .contact-label {
  min-width: 5rem;
  font-size: var(--fs-12);
  letter-spacing: .16em;
  color: var(--mist);
}

.page-about .contact-value {
  font-size: var(--fs-16);
  color: var(--fog);
  word-break: break-word;
}

.page-about .about-copy {
  margin-left: auto;
  padding: .18rem .7rem;
  font-family: var(--ff-body);
  font-size: var(--fs-12);
  letter-spacing: .08em;
  color: var(--sand);
  background: transparent;
  border: 1px solid rgba(230, 181, 102, .45);
  border-radius: var(--pill);
  cursor: pointer;
  transition: color .2s var(--ease), border-color .2s var(--ease), background-color .2s var(--ease);
}

.page-about .about-copy:hover,
.page-about .about-copy:focus-visible {
  color: var(--sea-950);
  background: var(--sand);
  border-color: var(--sand);
}

.page-about .about-copy.is-done {
  color: var(--sea-950);
  background: var(--teal);
  border-color: var(--teal);
}

/* ---------- responsive ---------- */

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

@media (min-width: 900px) {
  .page-about h1 {
    font-size: var(--fs-64);
  }

  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: end;
    gap: 3.5rem;
  }

  .page-about .about-chapter {
    grid-template-columns: 8rem minmax(0, 1fr);
    gap: 3rem;
    padding-block: clamp(3rem, 5.5vw, 4.75rem);
  }

  .page-about .about-rail {
    flex-direction: row;
    align-items: flex-start;
    gap: .6rem;
    position: sticky;
    top: 7rem;
    align-self: start;
  }

  .page-about .about-rot {
    writing-mode: vertical-rl;
    letter-spacing: .3em;
    font-size: .6875rem;
    padding-top: .4rem;
  }

  .page-about .about-body {
    border-left: 1px solid rgba(143, 169, 158, .18);
    padding-left: 2.5rem;
  }

  .page-about .about-body h2 {
    font-size: var(--fs-36);
  }

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

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

@media (min-width: 1180px) {
  .page-about .about-chapter {
    grid-template-columns: 9.5rem minmax(0, 1fr);
    gap: 4rem;
  }

  .page-about .about-index {
    font-size: 5.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .tl-mark::before,
  .page-about .tl-mark::after,
  .page-about .about-copy,
  .page-about a,
  .page-about .tl-item {
    transition: none;
  }
}
<<<END>>>

.page-about {
  --w: 1rem;
}