How to change LibreOffice default theme (instead of using Firefox persona) ?

Good day. I've been using themes on other open source programs like GIMP, Inkscape, Deluge, gPick and some more that use GTK 2.0 themes in Windows 7, and until now I just download the tar.gz file that contains the theme files from gnome-look.org and just unzip them in the folder usually located at AppFolder/etc/gtk-2.0/, the themes usually don't look 100% like they do in the previews (since I use Windows, not Linux) but it does make them look really good.

And I read about LibreOffice using GTK, but I don't find that folder, is it now KDE 4.0?, I'm confused because I don't know about this in greater detail, is it possible to change the theme by adding files to some folder in the app?, and if so, what kind of theme should I use?, and where's the folder where those files should go?. I like that the program can use Firefox personas to change the main bar, but that doesn't change the color scheme from the UI.