Right now if a project is only 1 day over capacity, the entire project falls below the line. It is deceiving when we're talking about major work, and confuses some of the teams who are looking at the road map. It would be much more useful if the line were static and projects passed through the line based on how much they could fit. That way we could determine if we were close/far and if through some minor scope adjustment could fit a project into a release.
Currently, the feature board shows the Capacity levels in two places. One is the capacity limit line as described. Another is towards the top of the page which shows the amount that the project is over capacity. We can understand the potential confusion that may arise with stakeholders.
However, because of current priorities and that this information is readily available (combined with the ability to view estimates on each card), we are unlikely to make changes in this area based on our current priorities. We hope you can understand.
I would not indicate how much of a feature fits into it, but simply which features fot ENTIRELY in the available capacity. Cramming in things until the buckets is as full as can be is just asking for trouble.
But of course, the detailed behavior w.r.t. the capacity cut off could be a parameter: "slice feature" or "keep features intact" :-)