JSFiddle - React, Tailwind, and code Playground

HTML

<div id="Ad">
<div id="Medium">
 <p>Aqui tu codigo del ad 468x60</p>
</div>
<div id="Large">
 <p>Aqui tu codigo del ad 720x90</p>
</div>
</div>

CSS

#Ad #Medium{
display:none;
}
@media (max-width: 800px) {
  #Ad #Medium {
    display: block;
  }
 #Ad #Large {
   display:none;
 }
}