Are you able to attach your workbook? I believe this can be solved by using a second metric and creating a dual axis chart. The second chart would be a square behind the circle and could be a highlight color for the days you indicated above.
Unfortunately not. The dashboard is highly sensitive. I like your idea and will try it when I get a chance!
Alright let me know how it works out.
I've created a mockup and added it to OP. I still can't get it to work.
I want my users to be able to see which days are special. We have two options: we can either color the background of the cell or change the shape. For example, if it is a holiday, we can color cell background pink or change the circle to a star. If there are multiple events on that day, we would color the background behind the circle to another color, or change it to a different shape and so on.