Present Edit Block Table of Contents as a popup

It would be nice to use a popup presentation when the Table of Contents button/link is clicked in the Edit Block. This can be done by adding the following CSS code to the theme. You may need to add a color: definition and change the background color and border to suit you needs. The Table of Contents button is a toggle. Clicking outside the menu does not make it go away.

div.books-blocks-edit-toc {
  display: block;
  padding: 0.5em 1em;
  background: white;
  position: absolute;
  z-index: 100;
  border: 2px solid black;
  margin-top: -1.6em;
  box-shadow: gray 4px 4px;