Hi Walter,
1. It is an unpopular feature for Gantt charts. In some other Gantt tools, it is called “sub-tasking” and when a project is closed, the subtasks are displayed instead of the project’s visual bar. We may probably add it during the process of updating the Gantt.
2. That is correct. There is no API for styling a specific cell.
Best regards,
Peter Stoev
Smart UI Team
https://www.htmlelements.com/