Out of the blue, Excel 2016 has started doing this.
When I typed 1.5 and hit Enter, the entire row got the top and bottom border. When I entered a number in E2 and then deleted it, the cell got a border all around.
These are phantom border. If you print-preview, they do not appear. They also do not appear under Format Cells, Borders. I'm wondering if this is some kind of accessibility feature that I inadvertently turned on. Has anyone seen anything like this?

When I typed 1.5 and hit Enter, the entire row got the top and bottom border. When I entered a number in E2 and then deleted it, the cell got a border all around.
These are phantom border. If you print-preview, they do not appear. They also do not appear under Format Cells, Borders. I'm wondering if this is some kind of accessibility feature that I inadvertently turned on. Has anyone seen anything like this?