Aguarin,
If you haven't figured out how to update those colors yet. From inside the site designer if you click on the Add to Calendar button the style options open on the right side. Click customize and you can choose the "pop up" window for full customization.
All those colors will originate in your theme colors as well.
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James Rose | Senior Web Developer and Platform/Product Manager
Digital Infrastructure
Office of University Development | University of Michigan
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