But I'm not making this post to digress about my personal tastes but more as a warning signpost for a bunch of online resources that, under the guise of UI customization, are no more than honeypots for ridding the unwary user with nasty adware or worse.
Case in point, as anyone who's ever read a customization tutorial will know, in order to be able apply to apply custom themes to Windows it has to be patched, normally done with a tool called UXTheme; to get it, as it has floated around the web in different versions over the years, the usual and quickest way is to google for it.
And this is where it gets hairy, as one might arrive a locations such
https://windowsxlive.net/uxtheme-multi-patcher/ will provide more reliable info -- as well as allow for user feedback. So as the saying goes (and this is my final point): customers beware, here be dragons...