b5d939565b
This part of the page can be scrolled independently with the mouse, and
so the same should be possible with a keyboard.
Axe was reporting this error:
```
1) scrollable-region-focusable: Scrollable region must have
keyboard access (serious)
https://dequeuniversity.com/rules/axe/4.11/scrollable-region-focusable?application=axeAPI
The following 1 node violate this rule:
Selector: .fullscreen > .markdown-preview.medium-6.small-12
HTML: <div class="small-12 medium-6 column markdown-preview">
Fix any of the following:
- Element should have focusable content
- Element should be focusable
```