/* Botón flotante "Volver al portfolio" compartido por todas las demos */
.back-to-portfolio {
  position: fixed;
  left: 16px;
  bottom: 16px;
  z-index: 2147483000;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 18px;
  border-radius: 999px;
  background: #0b1020;
  color: #f1f5f9;
  border: 1px solid rgba(94, 234, 212, .55);
  font: 600 14px/1 "Segoe UI", system-ui, -apple-system, Roboto, Arial, sans-serif;
  text-decoration: none;
  box-shadow: 0 10px 30px -8px rgba(0, 0, 0, .65);
  transition: transform .2s ease, background .2s ease, color .2s ease;
}
.back-to-portfolio:hover,
.back-to-portfolio:focus-visible {
  background: #5eead4;
  color: #05231f;
  transform: translateY(-2px);
  outline: none;
}
.back-to-portfolio:focus-visible { outline: 3px solid #fff; outline-offset: 2px; }
@media (max-width: 520px) {
  .back-to-portfolio { left: 10px; bottom: 10px; padding: 10px 14px; font-size: 13px; }
}