.stack-section {
  font-family: sans-serif;
  background: #white;
  padding-top: 10px;
  position: relative;
  padding: 0px;
}

.stack-wrapper {
  position: relative;
  width: 100%;
  margin-top: 60px;
}

.stack-wrapper h2 {
  color: white;
}

.card {
  position: sticky;
  top: 5vh;
  max-width: 800px;
  margin: 0 auto;
  padding: 60px;
  border-radius: 30px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
  margin-bottom: 100px; /* separación visible inicial */
  z-index: 1;
  transition: transform 0.3s ease;
}

/* Cartas específicas: estilo + apilado progresivo */
.card:nth-child(1) {
  background-color: #003068;
  color: white;
  top: 10vh;
  z-index: 1;
}
.card:nth-child(2) {
  background-color: #0d4f83;
  color: white;
  top: 10vh;
  z-index: 2;
}
.card:nth-child(3) {
  background-color: #003068;
  color: white;
  top: 15vh;
  z-index: 3;
}