.scrollspy-example {
  position: relative;
  height: 50vh;
  overflow: auto;
}

#NavBarFlash:hover
{
  opacity: 1;
  -webkit-animation: flash 1.5s;
  animation: flash 1.5s;
}
@-webkit-keyframes flash 
{
	0% {
        opacity: 0;
    	}
  100% {
        opacity: 1;
      }
}