That did it! Thank you TWICE for two fixes today! 
A note on the behavior: 100vh did nothing and 1000vh caused the scroll bar to behave undesirably (it would scroll down into nothingness). 200 also seemed like too much scroll distance, so I walked it up in increments of 10. Amusingly, the background did not replicate itself, thereby causing the khaki (normal) background to reappear, at bottom. This maintained until I reached 140vh.