When editing table borders in the Stroke panel, the small preview grid that represents the cell borders is very hard to see and use. The active line selection is indicated by a very thin and pale blue highlight, which is almost invisible on high-resolution or bright displays.
This makes it difficult to tell which borders are selected or to accurately click on them. The hit area for these lines is also extremely narrow, which further reduces usability.
It would be a major improvement if the highlight: had stronger color contrast or adjustable color (for example, a red or darker highlight), appeared thicker or bolder, or if there were a clearer visual indicator (e.g., a solid overlay or thicker outline).

This small adjustment would greatly improve visibility and usability when formatting tables in InDesign.