When the Copy button is pressed, focus is lost and scrolling the page

with the arrow keys stops working. Fixed by upgrading ClipboardJS to
the latest version

src/theme/book.js

@@ -543,7 +543,7 @@ function playpen_text(playpen) {
         elem.className = 'fa fa-copy tooltipped';
     }
 
-    var clipboardSnippets = new Clipboard('.clip-button', {
+    var clipboardSnippets = new ClipboardJS('.clip-button', {
         text: function (trigger) {
             hideTooltip(trigger);
             let playpen = trigger.closest("pre");