Requsting help finding the source of a phantom color

The close button on the slide-out sidebar has a hover color that isn’t associated with the theme and that I can’t seem to change independent of something else.

The button color is handled by the theme:

.color-scheme-radar_tweaked .site-palette-yin-1-background-color, .color-scheme-radar_tweaked a.site-palette-yin-1-background-color {
	background-color: #ffffff;
}

But the hover is handled by an inline style sheet and is grayed out in the inspector:

.md-button.md-default-theme.md-fab, .md-button.md-fab {
	background-color: rgb(255,64,129);
	color: rgb(255,255,255);
}

At first I thought to contact the theme creator, but the current hover color is one of my personal go-to accent colors; one that I might have used when the site was first created but would have definitely been replaced by a different color since then. Additionally, the theme in use now is not the original theme, and both the theme and WordPress have been updated several times over since I started using the theme, so any direct edits should have been erased. I believe I’ve looked through every setting and I can’t find the source of the color and I feel like I’m getting nowhere when I try looking at the theme CSS files in the editor. I have no active Snippets and nothing currently in Additional CSS is related to this or any other button or hover effect.

I tried adding the following to Additional CSS. It changes the hover, but also overrides the theme and it becomes a static color.

.md-button.md-default-theme.md-fab, .md-button.md-fab {
	background-color: rgb(16,186,153) !important;
}

So I’d like to learn one or both of the following:

1 How might I go about finding the source file of the color?

2 How can I target just the hover aspect?

Thanx.

The page I need help with: [log in to see the link]