overlapping divs in docs pages on tall, narrow windows

[aiuto]

Repo

• Create a window in portrait mode. Best done with a monitor in portrait mode
• open https://docs.bazel.build/versions/master/test-encyclopedia.html and scroll to "Initial Conditions"
• observe that
  • the table of environment variables hangs off the window edge (but there is scrollbar - good)
  • the table overlaps the right navigation.
  • the texts of both divs merge rather than the content pane occluding the navigation pane

Screenshot