/* ============================================================
   INTRO CAROUSEL
   ============================================================ */
.intro-shell { padding: 24px 28px 64px; max-width: 1360px; margin: 0 auto; }
.intro-eyebrow {
  display: flex; align-items: center; gap: 10px;
  font-family: "Geist Mono", monospace;
  font-size: 11px; letter-spacing: 0.16em; text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 14px;
}
.intro-eyebrow .dot {
  width: 6px; height: 6px; border-radius: 50%; background: var(--acc);
  animation: pulse 2.4s ease-in-out infinite;
}
@keyframes pulse { 50% { opacity: 0.4; } }

.stage-track {
  position: relative;
  border: 1px solid var(--rule);
  border-radius: 22px;
  background: var(--paper);
  overflow: hidden;
  box-shadow: 0 1px 0 rgba(0,0,0,0.02), 0 30px 60px -40px rgba(0,0,0,0.18);
}
.stage-viewport { overflow: hidden; }
.stage-rail {
  display: flex;
  transition: transform .55s cubic-bezier(.6,.05,.2,1);
  will-change: transform;
}
.stage {
  box-sizing: border-box;
  flex: 0 0 100%;
  width: 100%;
  padding: clamp(28px, 4vw, 52px) clamp(28px, 4.5vw, 60px);
  min-height: clamp(420px, calc(100vh - 240px), 600px);
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: clamp(24px, 4vw, 52px);
  align-items: center;
}
.stage > .lhs, .stage > .rhs { min-width: 0; }
.stage .art { max-width: 100%; height: auto; display: block; }
.stage .rhs > svg { max-width: 100%; max-height: 100%; height: auto; }
.stage .lhs .num {
  font-family: "Geist Mono", monospace;
  font-size: 12px; letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--acc);
  font-weight: 500;
}
.stage h2 {
  font-size: clamp(30px, 3.6vw, 52px);
  line-height: 0.98; letter-spacing: -0.035em;
  font-weight: 600;
  margin: 12px 0 14px;
  color: var(--ink);
}
.stage h2 em {
  font-style: normal;
  background: var(--brand-grad);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.stage p.lede {
  font-size: 15px; line-height: 1.55;
  color: var(--ink-2);
  max-width: 540px;
}
.stage ul.points {
  list-style: none; padding: 0; margin: 18px 0 0;
  display: flex; flex-direction: column; gap: 8px;
}
.stage ul.points li {
  padding-left: 22px; position: relative;
  font-size: 13px; line-height: 1.5; color: var(--ink-2);
}
.stage ul.points li::before {
  content: ""; position: absolute; left: 0; top: 8px;
  width: 12px; height: 1.5px; background: var(--acc);
}

.stage .rhs {
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: 16px;
  min-height: clamp(280px, 50vh, 420px);
  height: 100%;
  padding: 24px;
  display: flex; align-items: center; justify-content: center;
  position: relative;
  overflow: hidden;
}
.stage .rhs::before {
  content: "";
  position: absolute; inset: 0;
  background-image: radial-gradient(circle, rgba(24,23,26,0.08) 1px, transparent 1.4px);
  background-size: 18px 18px;
  mask-image: radial-gradient(ellipse 80% 70% at 50% 50%, black 50%, transparent 100%);
  pointer-events: none;
}

/* Carousel chrome */
.stage-chrome {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 28px;
  border-top: 1px solid var(--rule);
  background: var(--paper);
}
.dots { display: flex; gap: 8px; }
.dots button {
  width: 28px; height: 6px; border-radius: 3px;
  background: var(--rule); border: none;
  transition: background .2s, width .25s;
}
.dots button.active { background: var(--ink); width: 44px; }
.nav-btns { display: flex; gap: 8px; }
.nav-btns button {
  border: 1px solid var(--rule-strong);
  background: var(--paper);
  padding: 10px 16px;
  border-radius: 999px;
  font-size: 13px; font-weight: 500;
  display: inline-flex; align-items: center; gap: 8px;
  transition: background .15s, border-color .15s, transform .15s;
}
.nav-btns button:hover {
  border-color: var(--ink); background: var(--paper-2);
  transform: translateY(-1px);
}
.nav-btns button.primary {
  background: var(--ink); color: var(--bg);
  border-color: var(--ink);
}
.nav-btns button.primary:hover {
  background: color-mix(in oklab, var(--ink), white 15%);
}
.nav-btns button:disabled {
  opacity: 0.4; cursor: not-allowed; transform: none;
}
.stage-counter {
  font-family: "Geist Mono", monospace;
  font-size: 11px; letter-spacing: 0.1em;
  color: var(--muted);
}
.stage-counter b { color: var(--ink); font-weight: 500; }

/* ============================================================
   INTRO ART  — recreated Figures 2 & 3 as inline SVG
   ============================================================ */
.art { width: 100%; height: 100%; max-width: 480px; }

/* art:vision — three rings */
.ring-vision { display: grid; place-items: center; width: 100%; height: 100%; }
.ring-vision svg { width: 100%; height: auto; }

/* art:steps — 3-step ladder */
.ladder { display: flex; flex-direction: column; gap: 14px; width: 100%; padding: 4px; }
.ladder-step {
  display: grid;
  grid-template-columns: 56px 1fr;
  align-items: center; gap: 16px;
  padding: 16px 18px;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 12px;
  box-shadow: 0 1px 0 rgba(0,0,0,0.02);
}
.ladder-step .ln {
  width: 40px; height: 40px; border-radius: 12px;
  display: grid; place-items: center;
  background: color-mix(in oklab, var(--acc) 12%, var(--paper));
  color: var(--acc);
  font-family: "Geist Mono", monospace;
  font-weight: 600; font-size: 16px;
}
.ladder-step .lt { font-weight: 600; font-size: 15px; line-height: 1.2; }
.ladder-step .lp { font-size: 12.5px; color: var(--ink-2); margin-top: 2px; }
.ladder-arrow {
  height: 14px;
  background:
    linear-gradient(to bottom, var(--rule-strong) 0 1px, transparent 1px) center / 1px 14px no-repeat;
  margin-left: 28px;
}


/* ============================================================
   STAGE — BANNER VARIANT (full-width image stage)
   Used for Stage 02 where a wide reference figure is the focus.
   ============================================================ */
.stage.stage--banner {
  grid-template-columns: 1fr;
  gap: clamp(20px, 2.4vw, 32px);
  align-items: stretch;
  text-align: left;
}
.stage--banner .banner-head {
  max-width: 880px;
}
.stage--banner .banner-head .num {
  display: inline-block;
  font-family: "Geist Mono", monospace;
  font-size: 12px; letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--acc);
  font-weight: 500;
  margin-bottom: 6px;
}
.stage--banner .banner-head h2 {
  font-size: clamp(28px, 3.2vw, 44px);
  line-height: 0.98; letter-spacing: -0.035em;
  font-weight: 600;
  margin: 6px 0 12px;
  color: var(--ink);
}
.stage--banner .banner-head h2 em {
  font-style: normal;
  background: var(--brand-grad);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.stage--banner .banner-head .lede {
  font-size: 15px; line-height: 1.55;
  color: var(--ink-2);
  max-width: 720px;
}
.stage--banner .banner-fig {
  margin: 0;
  background: var(--paper-2);
  border: 1px solid var(--rule);
  border-radius: 16px;
  padding: clamp(16px, 2vw, 28px);
  display: flex; align-items: center; justify-content: center;
  overflow: hidden;
}
.stage--banner .banner-fig img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 56vh;
  object-fit: contain;
  border-radius: 8px;
}


/* ============================================================
   STAGE — STEP VARIANT (text + giant numeral, no chart)
   Used for Stages 03-05 (Step 01/02/03 deep-dives).
   ============================================================ */
.stage.stage--step {
  /* keep the two-column grid from the base .stage */
}
.stage--step .rhs--numeral {
  background:
    radial-gradient(ellipse 70% 60% at 50% 50%,
      color-mix(in oklab, var(--step-color, var(--acc)) 14%, transparent) 0%,
      transparent 60%),
    var(--paper-2);
  position: relative;
  overflow: hidden;
}
.stage--step .rhs--numeral::before {
  /* keep the dotted scrim from the base .stage .rhs::before */
}
.stage--step .step-numeral {
  position: relative;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  gap: 4px;
  color: var(--step-color, var(--acc));
  user-select: none;
}
.stage--step .sn-label {
  font-family: "Geist Mono", monospace;
  font-size: 11px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  opacity: 0.7;
}
.stage--step .sn-digit {
  font-family: "Geist", sans-serif;
  font-weight: 600;
  font-size: clamp(140px, 22vw, 240px);
  line-height: 0.86;
  letter-spacing: -0.05em;
  background: linear-gradient(180deg,
    color-mix(in oklab, var(--step-color, var(--acc)) 100%, transparent) 0%,
    color-mix(in oklab, var(--step-color, var(--acc)) 55%, transparent) 100%);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}