#btnTopo {
  width: 50px;
  height: 50px;
  position: fixed;
  bottom: 100px;
  right: 30px;
  z-index: 999;
  background-color: #0073e6;
  color: white;
  border: none;
  padding: 14px;
  border-radius: 50%;
  font-size: 20px;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease, transform 0.3s ease;
}

#btnTopo:hover {
  background-color: #005bb5;
  transform: scale(1.1);
}

#btnTopo.mostrar {
  opacity: 1;
  pointer-events: auto;
}