Hi @Mike 
As Szili mentioned in the other thread the solution would be the following 
- I’m posting here as well in case anyone else is interested in it
In the custom side panel you’ll have to imitate the layout of the calendar in order to achieve the similar outcome.
Here are some further ideas which might help you:
The side panel and the calendar should have a parent container which controls the height(and if it’s the case the width as well). This way both the calendar and the panel will have the same height. Here you can find a demo where there is a side panel displayed next to the calendar.
Inside the panel container create a column layout and add a fixed header part which will be the exact height as the calendar header + day names, and split the remaining space equally between the containers( where the weekly summaries will be) and this should align these container to the calendar day cells.(This will only work correctly with the default behavior of the calendar where the every cells have the same height).