Black background around icon in some dialog boxes

I've been using this WindowBlinds skin called The Windows Classic Theme by SemoB https://www.wincustomize.com/explore/windowblinds/9233/

And I notice that some dialog boxes like Error Checking in Drive properties and Copy and Replace have this black background around the arrow icon and not transparent, every time the dialog box opens :

When I hover my mouse over the icon, the black background disappears, and I want every time this kind of dialog box open it looks like this:

Any ways to remove the black background? Thank you!