<button onclick="myFunction()">Click me</button>

<div id="myPopup" style="display: none;">
  <p>This is the text in the popup.</p>
</div>

<script>
function myFunction() {
  var popup = document.getElementById("myPopup");
  if (popup.style.display === "none") {
    popup.style.display = "block";
  } else {
    popup.style.display = "none";
  }
}
</script> estilize esse codigo com css