TipKit: Change color of TipView close button?

Greetings,

I'm dipping a toe into TipKit and trying it out. I placed a TipView into one of my SwiftUI views, and the default styling didn't fit well within our app, so I changed the background and text colors. However, I can't find a way to change the color of the close button ("X"). Unfortunately, the default color is very hard to see against the background color that I selected.

Is it possible to set the color of that close button?

For the time being, I have created a TipViewStyle that replicates the default styling with my color changes applied, but this seems unnecessarily complex for something as simple as setting the color of that button.

Thanks!