'Let's practice' section in Chapter 04: Currying doesn't renderer correctly

Hi, I am reading the book using gitbook, thanks for this amazing book.

In chapter 04 (https://mostly-adequate.gitbook.io/mostly-adequate-guide/ch04), it is mentioned that I can practice the exercises in the browser itself..

But for some reason, the 'Let's practice' section is only partially rendered.

Kindly fix it, thank you.