New work form's fields and labels for chapter title and number are not properly associated

For the request more invites fields:

1. Log in

2. Visit Post > New Work

3. Check "This work has multiple chapters"

4. Click on the labels "Chapter 1 of" and "Chapter Title:"

What should happen
In many browsers, when you're using a mouse and you click a form field's label, it should place focus on the field.

What actually happens
None of that.