While working on MDL-85009, I have noticed a few issues with the table borders in the grader report.

1. Some borders within the user column become invisible, which creates a poor user experience by making it appear as though two different users are in the same (joined) table cell. I can only reproduce this once edit mode is enabled on the page, but this may not be the culprit.
   
2. The "sticky table" header no longer displays a top border as it did before. This issue occurs regardless of whether edit mode is enabled.