How to Avoid the Drop Shadow from a Custom HTML Prompt

Whenever you instantiate a Custom HTML Prompt, a drop-shadow circumscribes the window. You can avoid this by setting the Transparency flag, but then the visible items have a drop-shadow.

However, the drop-shadow is only applied to objects present during instantiation. So, if you delay all your drawing, nothing will have a drop-shadow.

You can do this with pure CSS (and then add a div tag in the HTML with this class selector):

.divbox {
  width: 60px;
  height: 60px;
  background-color: #ff6699;
  animation: 1s fadeIn;
  animation-fill-mode: forwards;
  visibility: hidden;