Visually, nothing should have changed.
Changes include
- Convert most `<a [no href]>` to `<button>` when (re-)viewing files
- `<a class="ui button">` can now be clicked (again?) using <kbd>Enter</kbd>
- The `(un)escape file`, the `expand section` and the `expand/collapse file`
  buttons can now be focused (and subsequently clicked using only the keyboard)
- Previously, pressing <kbd>Space</kbd> on the `View file` checkbox did
  nothing as this checkbox listened to the wrong event listener.
  Now, you can use the keyboard for this checkbox too.

The `add code comment` button has been left inaccessible for now as it
requires quite a bit of extra logic so that it is unhidden when it is
focused (you can otherwise focus it without seeing it as you are not
hovering on the corresponding line).

…iv>`