body {
  background-color: #000000;
  color: #00FF00;
  font-family: 'VT323', monospace;
  text-shadow: 0 0 5px #00FF00;
}
button {
  background: transparent;
  color: red;
  border: 2px solid red;
  padding: 10px;
  font-size: 16px;
  cursor: pointer;
  animation: flicker 1s infinite;
}

@keyframes flicker {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}