JSFiddle - React, Tailwind, and code Playground

HTML

<div id="detectMouse">
</div>

<div id="menuHeight" class="hidemenu">Menu</div>

CSS

.showmenu{
  color: red;
  font-size: 20px;
  top: 0px;
}

.hidemenu {
  color: red;
  top: -75px;
}

#detectMouse {
  width: 100%;
  background-color: blue;
  height: 20px;
  position: inline-block;
  position: top;
}

#menuHeight {
  position: fixed;
  height: 75px;
  right: 2.5%;
  z-index: 40;
  transition: top 350ms ease, bot 350ms ease;
}

JavaScript

jQuery('#detectMouse').hover(
  function () {
    jQuery('#menuHeight').removeClass('hidemenu').addClass('showmenu');
  }, 
);