Minor in comparison, but should be documented IMO:
The "CLEAR ALL" button in one's HOME page can visually "merge" with the display mode buttons to the left of it when the window size is short enough, but not enough to trigger the "responsive design" for smaller resolutions just yet (see image below).
To reproduce, gradually decrease the width of the browser window until the buttons start to merge together.
The screen is at 150% DPI, Firefox claims the width of the "body" element is 1012.4
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