Full screen mode hides bottom of pages, scrolling not possible

**Description**

Using full-screen mode hides just the smallest bit at the bottom of the pages behind the horizontal nav. This usually is nothing, but sometimes this hides ISBN, copyright, or page numbers. I believe this started in the past week to two weeks. It is not possible to scroll, so one must exit full screen to see this area.

**Evidence / Screenshot (if possible)**

> Include evidence of the problem or provide a screenshot.

**Expectation**

> What should be happening? What will it look like / how will it behave when fixed?
Full-screen content should be completely above the horizontal nav.
**Context**

> What operating system? What browser type and version?
macOS Catalina 10.15.5
Chrome Version 83.0.4103.116 (Official Build) (64-bit)

**Proposal & Constraints**

> What is the proposed solution / implementation? Is there a precedent of this approach succeeding elsewhere?

**Stakeholders**

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