Edit in JSFiddle

<div>
  <button>Clique aqui</button>
</div>

div {
  width: 300px;
  height: 300px;
  border-radius: 8px;
  border: 2px solid black;
  display: flex;
  align-items:center;
  justify-content: center;
}

div:hover {
  background-color: aqua;
}

button {
  font-size: 18px;
  font-weight: 600;
  background-color: blue;
  color: white;
  padding: 10px 20px;
  border-radius: 15px;
  border: none;
  cursor: pointer;
}

button:hover {
  background-color: red;
}