A choice of 11 different themes to choose from which will persist if you leave the site and return later (unless you delete the cookie).
If you are reading a story, the Table of Contents will remain in view as you scroll. (This feature can be disabled.)
If you are reading a story, you can set a bookmark which will automatically scroll to that point when you return to that story. You can set or reset a bookmark for each story in the collection. You can also delete each bookmark.
An enhanced experience from the tooltips, some of which even include images.