/* Signal Path — homepage climb section (B&W only) */
.signal-path {
  --sp-bg: #0a0a0a;
  --sp-fg: #f5f5f5;
  --sp-muted: rgba(245, 245, 245, 0.45);
  --sp-dim: rgba(245, 245, 245, 0.22);
  --sp-line: rgba(245, 245, 245, 0.18);
  --sp-lit: #ffffff;
  position: relative;
  background: var(--sp-bg);
  color: var(--sp-fg);
  overflow: hidden;
  padding: 100px 0 120px;
}

.signal-path::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.08'/%3E%3C/svg%3E");
  opacity: 0.35;
  pointer-events: none;
  mix-blend-mode: overlay;
}

.signal-path .container {
  position: relative;
  z-index: 1;
}

/* Hook */
.sp-hook {
  max-width: 720px;
  margin-bottom: 80px;
}

.sp-hook .subtitle {
  color: var(--sp-muted);
}

.sp-hook h2 {
  color: var(--sp-fg);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.sp-hook p {
  color: var(--sp-muted);
  font-size: 1.05rem;
  line-height: 1.65;
  margin: 0;
}

/* Layout: spine + content */
.sp-track {
  position: relative;
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 0 2rem;
}

.sp-spine-col {
  position: relative;
}

.sp-spine {
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 2px;
  height: 100%;
  background: var(--sp-line);
}

.sp-spine__progress {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 0%;
  background: var(--sp-lit);
  transform-origin: top center;
}

.sp-ai-ticks {
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.sp-ai-tick {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  width: 10px;
  height: 1px;
  background: var(--sp-dim);
}

.sp-ai-tick span {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 9px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--sp-dim);
  white-space: nowrap;
  width: 0;
  overflow: hidden;
}

@media (min-width: 1200px) {
  .sp-ai-tick span {
    width: auto;
    overflow: visible;
  }
}

.sp-body {
  min-width: 0;
}

/* Act gate */
.sp-act {
  position: relative;
  margin-bottom: 48px;
  padding-top: 24px;
}

.sp-act__gate {
  position: relative;
  margin-bottom: 36px;
  padding: 8px 0 24px;
  border-bottom: 1px solid var(--sp-line);
  opacity: 0.35;
  transform: translateY(12px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.sp-act.is-active .sp-act__gate,
.sp-act.is-lit .sp-act__gate,
.signal-path.is-static .sp-act__gate {
  opacity: 1;
  transform: none;
}

.sp-act__numeral {
  position: absolute;
  top: -0.15em;
  right: 0;
  font-size: clamp(4.5rem, 12vw, 8rem);
  font-weight: 800;
  line-height: 0.85;
  letter-spacing: -0.04em;
  color: transparent;
  -webkit-text-stroke: 1px var(--sp-dim);
  pointer-events: none;
  user-select: none;
  opacity: 0.55;
}

.sp-act__label {
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--sp-fg);
  margin-bottom: 0.35rem;
}

.sp-act__thesis {
  color: var(--sp-muted);
  font-size: 0.95rem;
  max-width: 520px;
  margin: 0;
  font-style: italic;
}

/* Nodes */
.sp-node {
  position: relative;
  padding: 0 0 40px 0;
  opacity: 0.28;
  transform: translateY(18px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}

.sp-node.is-lit,
.signal-path.is-static .sp-node {
  opacity: 1;
  transform: none;
}

.sp-node:last-child {
  padding-bottom: 8px;
}

.sp-node__mark {
  position: absolute;
  left: calc(-2rem - 36px - 5px);
  top: 0.35em;
  width: 10px;
  height: 10px;
  background: var(--sp-bg);
  border: 1.5px solid var(--sp-muted);
  transform: rotate(45deg);
  transition: background 0.4s ease, border-color 0.4s ease, box-shadow 0.4s ease;
}

.sp-node.is-lit .sp-node__mark,
.signal-path.is-static .sp-node__mark {
  background: var(--sp-lit);
  border-color: var(--sp-lit);
}

.sp-node__year {
  display: block;
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--sp-dim);
  margin-bottom: 0.5rem;
  transition: color 0.45s ease;
}

.sp-node.is-lit .sp-node__year,
.signal-path.is-static .sp-node__year {
  color: var(--sp-fg);
}

.sp-node__rung {
  display: block;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--sp-fg);
  margin-bottom: 0.65rem;
}

.sp-node__move {
  color: var(--sp-muted);
  font-size: 0.95rem;
  line-height: 1.55;
  margin: 0 0 0.5rem;
  max-width: 560px;
}

.sp-node__proof {
  color: var(--sp-fg);
  font-size: 0.9rem;
  font-weight: 600;
  margin: 0 0 0.75rem;
  max-width: 560px;
}

.sp-node__carry {
  display: block;
  color: var(--sp-dim);
  font-size: 0.88rem;
  font-style: italic;
  line-height: 1.55;
  max-width: 520px;
  margin: 0;
  opacity: 0;
  transform: translateY(6px);
  transition: opacity 0.5s ease 0.15s, transform 0.5s ease 0.15s, color 0.4s ease;
}

.sp-node.is-lit .sp-node__carry,
.signal-path.is-static .sp-node__carry {
  opacity: 1;
  transform: none;
  color: var(--sp-muted);
}

.sp-node--finale .sp-node__carry {
  display: none;
}

/* Payoff */
.sp-payoff {
  margin-top: 64px;
  padding-top: 48px;
  border-top: 1px solid var(--sp-line);
  opacity: 0.3;
  transform: translateY(20px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.sp-payoff.is-lit,
.signal-path.is-static .sp-payoff {
  opacity: 1;
  transform: none;
}

.sp-payoff__claim {
  max-width: 640px;
  margin-bottom: 2rem;
}

.sp-payoff__claim h3 {
  color: var(--sp-fg);
  font-weight: 800;
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  letter-spacing: -0.02em;
  margin-bottom: 0.75rem;
}

.sp-payoff__claim p {
  color: var(--sp-muted);
  font-size: 1rem;
  line-height: 1.65;
  margin: 0;
}

.sp-scoreboard {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.75rem;
  padding: 1.25rem 0 1.75rem;
  border-top: 1px solid var(--sp-line);
  border-bottom: 1px solid var(--sp-line);
  margin-bottom: 1.75rem;
}

.sp-scoreboard span {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--sp-muted);
}

.sp-scoreboard strong {
  display: block;
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--sp-fg);
  text-transform: none;
  margin-top: 0.2rem;
}

.sp-payoff__cta {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.sp-payoff__cta .btn-line,
.sp-payoff__cta .btn-main {
  border-color: var(--sp-fg);
  color: var(--sp-fg);
}

.sp-payoff__cta .btn-main {
  background: var(--sp-fg);
  color: var(--sp-bg);
}

.sp-payoff__cta .btn-line:hover {
  background: var(--sp-fg);
  color: var(--sp-bg);
}

.sp-payoff__cta .btn-main:hover {
  background: transparent;
  color: var(--sp-fg);
}

/* Mobile */
@media (max-width: 767.98px) {
  .signal-path {
    padding: 72px 0 88px;
  }

  .sp-track {
    grid-template-columns: 28px 1fr;
    gap: 0 1.25rem;
  }

  .sp-node__mark {
    left: calc(-1.25rem - 14px - 4px);
    width: 8px;
    height: 8px;
  }

  .sp-act__numeral {
    font-size: 4rem;
    opacity: 0.35;
  }

  .sp-hook {
    margin-bottom: 48px;
  }

  .sp-ai-tick span {
    display: none;
  }

  .sp-scoreboard {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem 1.25rem;
  }
}

/* Reduced motion: fully revealed */
@media (prefers-reduced-motion: reduce) {
  .sp-act__gate,
  .sp-node,
  .sp-node__carry,
  .sp-payoff {
    opacity: 1 !important;
    transform: none !important;
    transition: none !important;
  }

  .sp-spine__progress {
    height: 100% !important;
  }

  .sp-node__mark {
    background: var(--sp-lit);
    border-color: var(--sp-lit);
  }

  .sp-node__year {
    color: var(--sp-fg);
  }
}