Tweaked chapter list item styles

- Improves animation smoothness
- Changed animation slideup/down animations to use max-height instead of height
  to better avoid jutter at the end.
- Cleaned spacing to match page items in books listing.

resources/js/components/chapter-toggle.js

@@ -12,14 +12,14 @@ class ChapterToggle {
         const list = this.elem.parentNode.querySelector('.inset-list');
         this.elem.classList.add('open');
         this.elem.setAttribute('aria-expanded', 'true');
-        slideDown(list, 240);
+        slideDown(list, 180);
     }
 
     close() {
         const list = this.elem.parentNode.querySelector('.inset-list');
         this.elem.classList.remove('open');
         this.elem.setAttribute('aria-expanded', 'false');
-        slideUp(list, 240);
+        slideUp(list, 180);
     }
 
     click(event) {