refactor(ui): reduce the size of the 'close' and 'copy' buttons

- The close button in the TOC popup
- The copy button in the code block

_javascript/modules/components/toc/toc-mobile.js

@@ -62,6 +62,7 @@ export class TocMobile {
   static showPopup() {
     this.lockScroll(true);
     $popup.showModal();
+    $btnClose.blur();
     const activeItem = $popup.querySelector('li.is-active-li');
     activeItem.scrollIntoView({ block: 'center' });
   }