body {
  font-family: Arial, sans-serif;
  background-color: #222;
  color: white;
  text-align: center;
  padding: 50px;
  overflow: hidden;
}

h1 {
  font-size: 3rem;
  animation: rainbow 5s linear infinite;
}

@keyframes rainbow {
  0% { color: red; }
  20% { color: orange; }
  40% { color: yellow; }
  60% { color: green; }
  80% { color: blue; }
  100% { color: violet; }
}

button {
  padding: 15px 30px;
  font-size: 1.5rem;
  font-weight: bold;
  border: none;
  border-radius: 30px;
  cursor: pointer;
  outline: none;
  animation: buttonFlash 1s infinite alternate;
  transition: transform 0.2s;
}

@keyframes buttonFlash {
  0% { background-color: red; color: white; }
  25% { background-color: yellow; color: black; }
  50% { background-color: lime; color: white; }
  75% { background-color: blue; color: white; }
  100% { background-color: violet; color: white; }
}

button:hover {
  transform: scale(1.1);
}

.hidden {
  display: none;
  font-size: 2rem;
  color: #ffcc00;
  font-weight: bold;
  margin-top: 20px;
}