#s1.requirements-stage {
  --requirements-scene-height: clamp(560px, calc(100vh - 56px), 920px);
  --requirements-scroll-distance: 260vh;
  position: relative;
  height: calc(var(--requirements-scene-height) + var(--requirements-scroll-distance));
  min-height: 0;
  padding: 0;
  margin: 0;
  background: #000;
  color: #fff;
  scroll-margin-top: 56px;
}
#s1.requirements-stage::before,
#s1.requirements-stage::after { display: none; }

.requirements-scene {
  position: sticky;
  top: 56px;
  isolation: isolate;
  width: 100%;
  height: var(--requirements-scene-height);
  overflow: hidden;
  background: #000;
}
.requirements-scene::before {
  content: '';
  position: absolute;
  z-index: 1;
  inset: 0;
  height: max(100%, calc(100dvh + 5.2083333333vw));
  pointer-events: none;
  background: url('./particle-mask.webp') center / cover no-repeat;
}
.requirements-particles {
  position: absolute;
  z-index: 0;
  inset: 0;
  width: 100%;
  /* Match the reference's full-window camera aspect inside the header iframe. */
  height: max(100%, calc(100dvh + 5.2083333333vw));
  opacity: 1;
  pointer-events: none;
}

.requirements-intro {
  position: absolute;
  z-index: 4;
  top: 11.5%;
  left: clamp(46px, 8.7vw, 150px);
  width: min(39vw, 520px);
}
.requirements-kicker {
  display: block;
  margin-bottom: 2.4vh;
  color: #8b829d;
  font: 500 10px/1.2 var(--mono);
  letter-spacing: .16em;
}
.requirements-intro h3 {
  width: max-content;
  margin: 0;
  color: transparent;
  background: linear-gradient(96deg, #5744ff 0%, #9587ff 53%, #eeeaff 100%);
  -webkit-background-clip: text;
  background-clip: text;
  font-size: clamp(48px, 6.2vw, 96px);
  font-weight: 500;
  line-height: 1.02;
  letter-spacing: 0;
}
.requirements-intro > p {
  margin: 3.1vh 0 0;
  color: #d8d3e1;
  font-size: clamp(16px, 1.3vw, 21px);
  font-weight: 400;
  line-height: 1.6;
}
.requirements-summary {
  width: min(100%, 440px);
  margin-top: 12px;
  color: #8f8999;
  font-size: clamp(11px, .85vw, 14px);
  font-weight: 300;
  line-height: 1.9;
}
.requirements-intro > * {
  opacity: 0;
  filter: blur(10px);
  transform: translateY(24px);
  transition: opacity .8s ease, filter .8s ease, transform 1s cubic-bezier(.16,1,.3,1);
}
.requirements-scene.is-visible .requirements-intro > * { opacity: 1; filter: none; transform: none; }
.requirements-scene.is-visible .requirements-intro h3 { transition-delay: .12s; }
.requirements-scene.is-visible .requirements-intro > p { transition-delay: .24s; }
.requirements-scene.is-visible .requirements-summary { transition-delay: .48s; }

.requirements-stack {
  position: absolute;
  z-index: 5;
  isolation: isolate;
  top: 10.5%;
  right: clamp(42px, 6.8vw, 118px);
  width: min(43vw, 620px);
  height: 620px;
}
.requirements-stack::before {
  content: '';
  position: absolute;
  z-index: -1;
  inset: -42px -58px -54px;
  background: linear-gradient(90deg, transparent, rgba(0,0,0,.72) 14%, rgba(0,0,0,.8) 54%, rgba(0,0,0,.6) 84%, transparent);
  filter: blur(14px);
  pointer-events: none;
}
.requirements-detail { display: none!important; }
.requirements-card {
  position: absolute;
  top: 0;
  left: 0;
  display: grid;
  grid-template-columns: 44px minmax(0,1fr);
  gap: 16px;
  align-items: center;
  width: 100%;
  min-height: 118px;
  padding: 18px 0 20px;
  border: 0;
  background: none;
  box-shadow: none;
  color: #fff;
  text-align: left;
  cursor: default;
  pointer-events: none;
  opacity: 0;
  visibility: hidden;
  transform: translate3d(0, 52px, 0) scale(.985);
  will-change: transform, opacity;
  transition: transform .72s cubic-bezier(.16,1,.3,1), opacity .42s ease, visibility 0s linear .72s, border-color .35s ease, background .35s ease;
}
.requirements-card.is-visible {
  pointer-events: auto;
  opacity: 1;
  visibility: visible;
  transform: translate3d(0, 0, 0) scale(1);
  transition-delay: 0s, 0s, 0s, 0s, 0s;
}
.requirements-card.is-past {
  transform: translate3d(0, -52px, 0) scale(.985);
}
.requirements-card.is-visible.is-preview {
  pointer-events: none;
  opacity: .42;
  transform: translate3d(10px, var(--requirements-preview-y, 340px), 0) scale(.97);
  filter: blur(.2px);
}
.requirements-card.is-preview {
  background: none;
  box-shadow: none;
}
.requirements-card.is-active {
  grid-template-columns: minmax(0,1fr);
  min-height: 440px;
  padding: 30px 46px 26px 60px;
  border: 1px solid rgba(173, 154, 255, .28);
  border-radius: 14px;
  background: linear-gradient(112deg, rgba(22, 17, 48, .92), rgba(7, 6, 19, .86));
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, .06), 0 18px 48px rgba(0, 0, 0, .24);
  backdrop-filter: blur(8px);
}
.requirements-card:hover:not(.is-active) { border-color: transparent; }
.requirements-card:focus-visible { outline: 2px solid #a895ff; outline-offset: 4px; }
.requirements-card-number {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border: 1px solid rgba(190,174,220,.2);
  border-radius: 50%;
  color: #c3b9d5;
  font: 500 11px/1 var(--mono);
  transition: color .35s ease, border-color .35s ease, box-shadow .35s ease;
}
.requirements-card.is-active .requirements-card-number {
  position: absolute;
  z-index: 2;
  top: 24px;
  right: 24px;
  color: #fff;
  border-color: #9a83ff;
  background: rgba(117,83,255,.14);
  box-shadow: 0 0 0 6px rgba(117,83,255,.05), 0 0 28px rgba(117,83,255,.38);
}
.requirements-card.is-active .requirements-card-copy {
  grid-column: 1;
}
.requirements-card.is-active .requirements-card-copy > strong,
.requirements-card.is-active .requirements-card-copy > small {
  padding-right: 58px;
}
.requirements-card.is-active .requirements-card-copy > strong {
  font-size: 22px;
  line-height: 1.3;
}
.requirements-card-copy { min-width: 0; }
.requirements-card-copy strong {
  display: block;
  color: #eeebf3;
  font-size: clamp(15px, 1.25vw, 19px);
  font-weight: 500;
  line-height: 1.25;
}
.requirements-card-copy small {
  display: -webkit-box;
  margin-top: 8px;
  overflow: hidden;
  color: #a59fad;
  font-size: clamp(11px, .82vw, 13px);
  font-weight: 300;
  line-height: 1.55;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}
.requirements-card.is-active .requirements-card-copy small {
  display: block;
  margin-top: 10px;
  overflow: visible;
  color: #ddd8e8;
  font-size: 17px;
  line-height: 1.7;
  -webkit-line-clamp: unset;
}
.requirements-card-details {
  display: none;
  margin-top: 14px;
  padding-top: 0;
  border-top: 0;
}
.requirements-card.is-active .requirements-card-details {
  display: grid;
  gap: 0;
  margin-top: 18px;
  padding-top: 0;
}
.requirements-card-details > span {
  display: grid;
  grid-template-columns: 68px minmax(0,1fr);
  gap: 10px;
  align-items: start;
  position: relative;
}
.requirements-card-details b,
.requirements-card-details i {
  font-size: clamp(12px, .88vw, 14px);
  font-style: normal;
  font-weight: 300;
  line-height: 1.55;
}
.requirements-card.is-active .requirements-card-details b,
.requirements-card.is-active .requirements-card-details i { line-height: 1.65; }
.requirements-card.is-active .requirements-card-details b {
  font-size: 16px;
  font-weight: 500;
}
.requirements-card.is-active .requirements-card-details i {
  font-size: 17px;
}
.requirements-card-details b { color: #a795ef; }
.requirements-card-details b { white-space: nowrap; }
.requirements-card-details i { color: #e0dbe7; }
.requirements-card-details > span:nth-child(1) {
  grid-template-columns: 88px minmax(0,1fr);
  padding: 15px 0 14px;
  border-top: 1px dashed rgba(167,139,239,.28);
}
.requirements-card-details > span:nth-child(1) b {
  display: flex;
  align-items: center;
  gap: 9px;
  color: #b197ff;
}
.requirements-card-details > span:nth-child(1) b::before {
  content: '';
  width: 5px;
  height: 5px;
  flex: none;
  border-radius: 50%;
  background: #b197ff;
  box-shadow: 7px 0 0 rgba(177,151,255,.62), 3px -6px 0 rgba(177,151,255,.36);
}
.requirements-card-details > span:nth-child(2) {
  grid-template-columns: 82px minmax(0,1fr);
  padding: 13px 0 13px 15px;
  border-left: 2px solid #28c7eb;
  background: linear-gradient(90deg, rgba(40,199,235,.1), rgba(40,199,235,.025) 58%, transparent);
}
.requirements-card-details > span:nth-child(2) b {
  color: #35d0f2;
  font-weight: 500;
}
.requirements-card-details > span:nth-child(2) i {
  color: #d0cbd8;
}
.requirements-card-details > span:nth-child(3) {
  grid-template-columns: 88px minmax(0,1fr);
  margin-top: 3px;
  padding-top: 14px;
  border-top: 1px solid rgba(255,255,255,.07);
}
.requirements-card-details > span:nth-child(3) b { color: #b7adbf; }
@media (max-width: 900px) {
  #s1.requirements-stage { height: auto; }
  .requirements-scene { position: relative; top: auto; height: auto; min-height: 940px; padding: 64px 24px 72px; }
  .requirements-intro { position: relative; inset: auto; width: 100%; }
  .requirements-intro h3 { font-size: clamp(44px, 12vw, 72px); }
  .requirements-summary { margin-top: 36px; }
  .requirements-stack { position: relative; inset: auto; display: grid; gap: 14px; width: 100%; height: auto; margin-top: 58px; }
  .requirements-stack::before { inset: -30px -20px; opacity: .68; }
  .requirements-card,
  .requirements-card.is-visible,
  .requirements-card.is-past,
  .requirements-card.is-visible.is-preview {
    position: relative;
    min-height: 108px;
    pointer-events: auto;
    opacity: 1;
    visibility: visible;
    transform: none;
    filter: none;
  }
  .requirements-card-details { display: grid; gap: 9px; }
}
@media (max-width: 480px) {
  .requirements-scene { min-height: 890px; padding-inline: 18px; }
  .requirements-kicker { font-size: 9px; }
  .requirements-intro > p { font-size: 15px; }
  .requirements-summary { font-size: 12px; }
  .requirements-card { grid-template-columns: 38px minmax(0,1fr); gap: 12px; padding: 22px 0 24px; }
  .requirements-card-number { width: 34px; height: 34px; }
}
@media (prefers-reduced-motion: reduce) {
  .requirements-intro > * { opacity: 1; filter: none; transform: none; transition: none; }
  .requirements-card { transition: none; }
}

/* This background layer exists only for the hero → roadmap → discovery trip.
   Content keeps its own stacking context above the traveling particles. */
.particle-journey-layer {
  position: fixed;
  z-index: 0;
  top: 0;
  left: 0;
  width: 100%;
  overflow: hidden;
  pointer-events: none;
  background: transparent;
}
.particle-journey-layer[hidden] { display: none; }
.particle-journey-layer > .requirements-particles { height: 100%; }
.particle-journey-layer::after {
  content: '';
  position: absolute;
  z-index: 1;
  inset: 0;
  background: url('./particle-mask.webp') center / cover no-repeat;
  transform: translateY(var(--journey-mask-y, 0px));
  opacity: var(--journey-mask-opacity, 0);
}
.particle-journey-active body { background: #000; }
.particle-journey-active .qronos-hero { overflow: visible; }
.particle-journey-active #stagelist,
.particle-journey-active #s1.requirements-stage,
.particle-journey-active .requirements-scene { background: transparent; }
.particle-journey-active .requirements-scene::before { opacity: 0; }