body {
    padding: 1.5rem;
}

.greeting {
    font-family: 'Shantell Sans', cursive;
    text-align: center;
    width: 100%;
    font-size: 2rem;
    animation: fadeInOut 3s ease-in-out infinite;
}

@keyframes fadeInOut {
    0% {
      opacity: 0;
    }
    50% {
      opacity: 1;
    }
    100% {
      opacity: 0;
    }
  }

  audio {
    display: block;
    margin: 0 auto;
    max-width: 100%;
    border-radius: 1rem;
  }

.cat-gif {
    max-width: 50%;
    height: auto;
    display: none;
    margin: 1rem auto;
    border-radius: 1rem;
}

.birthday-button {
  display: block;
  margin: 0 auto;
    background-color: white;
    color: black;
    border-radius: 10em;
    font-size: 17px;
    font-weight: 600;
    padding: 1em 2em;
    cursor: pointer;
    transition: all 0.3s ease-in-out;
    border: 1px solid black;
    box-shadow: 0 0 0 0 black;
  }
  
  .birthday-button:hover {
    transform: translateY(-4px) translateX(-2px);
    box-shadow: 2px 5px 0 0 black;
  }
  
  .birthday-button:active {
    transform: translateY(2px) translateX(1px);
    box-shadow: 0 0 0 0 black;
    -webkit-transform: translateY(2px) translateX(1px);
    -moz-transform: translateY(2px) translateX(1px);
    -ms-transform: translateY(2px) translateX(1px);
    -o-transform: translateY(2px) translateX(1px);
}