@keyframes soft-flash {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.7;
  }
}

.slow-flash {
  animation: soft-flash 2s infinite ease-in-out;
}

.flash {
  animation: soft-flash 1s infinite ease-in-out;
}

.fast-flash {
  animation: soft-flash 0.5s infinite ease-in-out;
}