* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: radial-gradient(circle at top, #1b2735 0, #090a0f 60%);
  color: #f5f5f5;
  min-height: 100vh;
}

header {
  text-align: center;
  padding: 2rem 1rem 1rem;
}

header h1 {
  font-size: 1.9rem;
  letter-spacing: 1px;
}

.sub {
  margin-top: 0.5rem;
  color: #c7d2fe;
  font-size: 0.95rem;
}

main {
  max-width: 800px;
  margin: 0 auto;
  padding: 1rem 1.5rem 3rem;
}

.card {
  background: rgba(15, 23, 42, 0.9);
  border-radius: 12px;
  padding: 1.5rem 1.7rem;
  margin-top: 1.5rem;
  box-shadow: 0 18px 40px rgba(0, 0, 0, 0.45);
  display: none;
}

.card.active {
  display: block;
  animation: fadeIn 0.5s ease-out;
}

.card h2 {
  margin-bottom: 0.8rem;
  font-size: 1.4rem;
  color: #e5e7eb;
}

.card p {
  margin-bottom: 0.7rem;
  line-height: 1.5;
}

blockquote {
  border-left: 4px solid #f97316;
  padding-left: 0.8rem;
  margin: 0.8rem 0;
  font-style: italic;
  color: #fed7aa;
}

.code {
  font-family: "Courier New", monospace;
  background: rgba(15, 23, 42, 0.8);
  padding: 0.4rem 0.6rem;
  border-radius: 6px;
  display: inline-block;
  margin-bottom: 0.7rem;
}

.firma {
  margin-top: 0.8rem;
  font-weight: 600;
  color: #facc15;
}

button {
  cursor: pointer;
  border: none;
  border-radius: 999px;
  padding: 0.6rem 1.2rem;
  font-size: 0.95rem;
  margin-top: 0.6rem;
  transition: transform 0.1s ease, box-shadow 0.1s ease, background 0.2s;
}

.btn-next,
.btn-choice,
#btnComenzar,
#btnReiniciar {
  background: linear-gradient(135deg, #f97316, #facc15);
  color: #111827;
  font-weight: 600;
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.4);
}

.btn-choice {
  margin-right: 0.4rem;
  margin-bottom: 0.4rem;
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 22px rgba(0, 0, 0, 0.5);
}

button:active {
  transform: translateY(1px);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.4);
}

.choice-container {
  margin-top: 0.8rem;
}

/* Overlay inicial */
.overlay {
  position: fixed;
  inset: 0;
  background: radial-gradient(circle at top, #020617 0, #000 60%);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
}

.overlay-content {
  max-width: 600px;
  background: rgba(15, 23, 42, 0.95);
  padding: 2rem 2.2rem;
  border-radius: 16px;
  text-align: center;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.7);
}

.overlay-content h1 {
  font-size: 1.6rem;
  margin-bottom: 0.8rem;
}

.overlay-content p {
  margin-bottom: 1rem;
  line-height: 1.5;
  color: #e5e7eb;
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.8rem;
  color: #9ca3af;
}

/* Animación */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Responsive */
@media (max-width: 600px) {
  main {
    padding: 0.5rem 1rem 2.5rem;
  }

  .card {
    padding: 1.2rem 1.3rem;
  }

  header h1 {
    font-size: 1.5rem;
  }
}