Course Presentation - Progress Bar Custom Colors CSS - Cannot Identify Selector

Hello,

I am trying to change the colors of the progress bar buttons in a course presentation.  I have been able to effectively change the colors of the "un-visited" buttons from the default grey, and the "active" or hover color. However, I cannot seem to identify or target the CSS selector to change the default blue color of the current / active slide - which is also the color representing "visited" slides.   Wondering if someone might be able to help me out?

The course presentation will ultimately be embedded in D2L Brightspace. However, I am currently just testing in a local HTML document.

Thanks!