JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
  <div class="block1">
    Block 1
    <input id="ib">
    <div class="popup">
      PopUp Block
    </div>
  </div>
  <label for="ib">
    <div class="block2">
      Block 2
    </div>
  </label>
</div>

CSS

.popup{
  display:none;
}
#ib{
  width:1px;
  height:1px;
  border:0;
  margin:0;
  height:0;
}
#ib:hover~.popup{
  display:block;
}