/* =======================================================
   stack.css · Sticky stack reveal de cards aurora
   ======================================================= */

.stack-section {
  position: relative;
  padding-block: var(--section-pad-y) calc(var(--section-pad-y) * 0.5);
}

.stack-intro {
  max-width: 760px;
  margin: 0 auto var(--space-10);
  text-align: center;
}
.stack-intro h2 {
  font-size: var(--fs-display);
  margin: var(--space-3) 0 var(--space-4);
  line-height: 1.04;
}
.stack-intro h2 .accent {
  background: var(--grad-aurora);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.stack-intro .lead {
  font-size: var(--fs-lead);
  color: var(--color-text-muted);
  max-width: 56ch;
  margin-inline: auto;
}
.stack-intro .hint {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: var(--space-5);
  font-family: var(--font-display);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semi);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-brand);
}
.stack-intro .hint svg { animation: nudgeDown 1.8s ease-in-out infinite; }
@keyframes nudgeDown {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(4px); }
}

/* ===== Container del stack ===== */
.stack-track {
  position: relative;
  /* Cada card aporta ~85vh de altura para que el sticky tenga recorrido */
  --card-scroll: 85vh;
}

/* ===== Card sticky ===== */
.stack-card {
  position: sticky;
  top: var(--stack-top);
  margin-bottom: var(--card-scroll, 85vh);
  height: var(--stack-card-h);
  border-radius: clamp(20px, 2.4vw, 32px);
  overflow: hidden;
  background: var(--glass-bg-strong);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(var(--blur-lg)) saturate(160%);
  -webkit-backdrop-filter: blur(var(--blur-lg)) saturate(160%);
  box-shadow: var(--shadow-elev);
  display: flex;
  align-items: stretch;
  isolation: isolate;
  will-change: transform;
}
.stack-card:last-child { margin-bottom: 0; }

/* Tinte aurora distinto por card (color de fondo y glow) */
.stack-card[data-tint="violet"]  { --tint-1: var(--aurora-violet);  --tint-2: var(--aurora-indigo); --tint-glow: rgba(139, 92, 246, .25); }
.stack-card[data-tint="cyan"]    { --tint-1: var(--aurora-cyan);    --tint-2: var(--aurora-teal);   --tint-glow: rgba(6, 182, 212, .22); }
.stack-card[data-tint="magenta"] { --tint-1: var(--aurora-magenta); --tint-2: var(--aurora-violet); --tint-glow: rgba(236, 72, 153, .22); }
.stack-card[data-tint="indigo"]  { --tint-1: var(--aurora-indigo);  --tint-2: var(--aurora-cyan);   --tint-glow: rgba(99, 102, 241, .22); }
.stack-card[data-tint="teal"]    { --tint-1: var(--aurora-teal);    --tint-2: var(--aurora-cyan);   --tint-glow: rgba(20, 184, 166, .20); }

/* Aurora background dentro de cada card */
.stack-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 18% 20%, var(--tint-1) 0%, transparent 55%),
    radial-gradient(circle at 80% 80%, var(--tint-2) 0%, transparent 55%);
  opacity: 0.6;
  z-index: 0;
  pointer-events: none;
}

/* Layout interno: 2 columnas */
.stack-inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: clamp(24px, 4vw, 56px);
  align-items: center;
  width: 100%;
  height: 100%;
  padding: clamp(28px, 4vw, 56px);
}

/* Lado izquierdo: copy */
.stack-copy {
  display: flex; flex-direction: column;
  gap: var(--space-4);
}
.stack-copy .stack-num {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-display);
  font-size: var(--fs-xs);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  font-weight: var(--fw-semi);
}
.stack-copy .stack-num strong {
  color: var(--color-text);
  font-size: 1rem;
  font-weight: var(--fw-bold);
}
.stack-copy .stack-num .dash {
  display: inline-block;
  width: 32px; height: 2px;
  background: var(--grad-aurora);
  border-radius: 1px;
}
.stack-copy h3 {
  font-family: var(--font-display);
  font-size: var(--fs-section);
  font-weight: var(--fw-bold);
  letter-spacing: -0.02em;
  line-height: 1.05;
  color: var(--color-text);
}
.stack-copy h3 em {
  font-style: italic;
  background: var(--grad-aurora);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.stack-copy p {
  color: var(--color-text);
  opacity: 0.85;
  font-size: var(--fs-lead);
  line-height: 1.55;
  max-width: 50ch;
}
.stack-copy .stack-meta {
  display: flex; flex-wrap: wrap;
  gap: var(--space-4) var(--space-6);
  margin-top: var(--space-3);
}
.stack-copy .stack-meta .m strong {
  display: block;
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: var(--fw-bold);
  letter-spacing: -0.02em;
  background: var(--grad-aurora);
  -webkit-background-clip: text; background-clip: text;
  color: transparent;
}
.stack-copy .stack-meta .m span {
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-weight: var(--fw-semi);
}
.stack-copy .stack-features {
  display: grid;
  gap: var(--space-3);
  margin-top: var(--space-3);
  list-style: none;
}
.stack-copy .stack-features li {
  display: flex; align-items: flex-start; gap: 10px;
  font-size: var(--fs-sm);
  color: var(--color-text);
  line-height: 1.5;
}
.stack-copy .stack-features li svg {
  flex-shrink: 0;
  margin-top: 3px;
  color: var(--color-brand);
}

/* Lado derecho: visual (mockup celular) */
.stack-visual {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}
.stack-visual::before {
  content: "";
  position: absolute;
  inset: 10%;
  background: radial-gradient(circle, var(--tint-glow) 0%, transparent 65%);
  filter: blur(40px);
  z-index: -1;
}