The closest thing to transparent is the grey color that you can select. There are some other work around methods that get a better result however. If you use GlobiFlow or a developer who understands the API, then you can have two date fields in your app.
- First date field is for active projects, and appears in calendar with the color of the associated status
- Second date field is for inactive projects, and does not appear in the calendar.
Once you've updated your app you can create a GlobiFlow flow, or a developer could make a custom script that will run anytime someone updates the status of the item in your pipeline. If that status is complete, then set the active date field to empty and set the inactive date field to match what was in the Active date field.
If you have any questions feel free to reach out to me at email@example.com, and we can set up a conference call to do a screenshare.
All the best!