* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  width: 100%;
  height: 100%;
}

body {
  overflow: hidden;
  font-family: Arial, Helvetica, sans-serif;

  /* Moving rainbow background */
  background: linear-gradient(
    -45deg,
    #ff9a9e,
    #fad0c4,
    #fbc2eb,
    #a6c1ee,
    #84fab0,
    #fddb92
  );

  background-size: 400% 400%;
  animation: rainbow 15s ease infinite;
}

main {
  width: 100%;
  height: 100%;

  display: flex;
  align-items: center;
  justify-content: center;

  padding: 30px;
}

#message {
  font-size: clamp(2.5rem, 8vw, 7rem);
  font-weight: 500;
  text-align: center;
  letter-spacing: -0.04em;

  opacity: 1;
  transition: opacity 1.2s ease;
}

#message.fade-out {
  opacity: 0;
}

@keyframes rainbow {
  0% {
    background-position: 0% 50%;
  }

  50% {
    background-position: 100% 50%;
  }

  100% {
    background-position: 0% 50%;
  }
}