body {
  background: #f0f0f0;
  font-family: 'Segoe UI', sans-serif;
  text-align: center;
  padding: 2rem;
}

.flag {
  position: relative;
  width: 320px;
  height: 180px;
  margin: 0 auto 1rem;
  border: 2px solid #333;
  overflow: hidden;
  animation: wave 3s infinite ease-in-out;
}

.stars {
  position: absolute;
  width: 40%;
  height: 50%;
  background: navy;
  background-image: radial-gradient(white 2px, transparent 2px);
  background-size: 20px 20px;
}

.stripes {
  position: absolute;
  width: 100%;
  height: 100%;
  background: repeating-linear-gradient(
    red 0px,
    red 14px,
    white 14px,
    white 28px
  );
}

button {
  padding: 0.6rem 1.2rem;
  font-size: 1rem;
  background: navy;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
}

#message {
  margin-top: 1rem;
  font-size: 1.2rem;
  color: #333;
  transition: opacity 1s ease;
}

.hidden {
  opacity: 0;
}

.visible {
  opacity: 1;
}

@keyframes wave {
  0%, 100% { transform: rotate(0deg); }
  50% { transform: rotate(1deg); }
}