The lack of navigation to move around the e-book site is considered an accessibility issue (see WCAG 2.2 Level AA: Multiple Ways).
Consider adding navigation at the top or even making the Lullabot logo link to the homepage of the ebook site rather than lullabot.com. When you're in an e-book, a link back to the table of contents for that ebook would also be really useful.
The lack of navigation to move around the e-book site is considered an accessibility issue (see WCAG 2.2 Level AA: Multiple Ways).
Consider adding navigation at the top or even making the Lullabot logo link to the homepage of the ebook site rather than lullabot.com. When you're in an e-book, a link back to the table of contents for that ebook would also be really useful.