Good evening Joshua and welcome back!
Thank you for reaching out to us.
I would love to help you with this topic.
The CSS code to tweak is the following:
.single-tribe_events .tribe-events-event-meta {
background: #e4e2e6;
}
You could replace it by something like
.single-tribe_events .tribe-events-event-meta {
background: #fff;
}
As for the Monday tooltip still being transparent, I would suggest the following CSS rule
#tribe-events-content.tribe-events-month .tribe-events-tooltip {
background-color: #fff;
}
Let me know if that helps.
Have a great day!
Geoff B.