JSFiddle - React, Tailwind, and code Playground

HTML

<div id="disque">
  <div id="menu"></div>
  <div id="yellow"></div>
</div>

CSS

#menu, #yellow{
  position: fixed;
  top: 2.5vw;
  right: 2.5%;
  height: 25px;
  width: 25px;
  border-radius: 30px;
}

#menu{
  animation: blink 2s infinite;
  transition: 1s;
  visibility: visible;
}

@keyframes blink{
  0% { background-color: grey; }
  50% { background-color: black; }
  100% { background-color: grey; }
}

#yellow{
  visibility: hidden;
  background-color: rgba(255, 0, 0, 0);
  transition: 1s;
}

#disque:hover #yellow{
  visibility: visible;
  pointer-events: none;
  background-color: rgba(255, 0, 0, 1);
}

#disque:hover #menu{
  visibility: hidden;
  opacity: 0;
}