* {
  box-sizing: border-box;
}

.week-09 {
  cursor: none;
}

.week-09 main {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 80vh;
  text-transform: capitalize;
}

.week-09 main .balloon {
  width: 100px;
  height: 100px;
  background-color: red;
  border-radius: 50%;
  position: relative;
  animation: breathing 16s infinite;
}

@keyframes breathing {
  0% {
    transform: scale(1);
  }
  25% {
    transform: scale(2);
  }
  50% {
    transform: scale(2);
  }
  75% {
    transform: scale(1);
  }
  100% {
    transform: scale(1);
  }
}