The window border of some application windows (I think based in GNOME, but not all) is about 12 (yes, about 30 pixels) times thicker than native applications with QT, and don’t know how to fix it. This are some of these applications:
Chrome browser, Brave browser, Microsoft Edge 4 linux browser (but not Chromium, Firefox or Opera)
Go into kde’s configurations setting and check Appearance/Application Style and click on Window Decorations. at the bottom of the dialog there should be a box to check/uncheck labeled Use Theme’s Window Default Border Size with a combo box to adjust borders manually. Try applying some changes here and see if it resolves the problem. (Or if it makes it worse!)
You may need to select a different theme as there may be an error or bug in the current one you are using. let us know what you find.
Thanks AdmFubar. I had been trying what you wrote here before asking, even “Configure GNOME/GTK applications style” preferences. The only thing I didn’t try was to enable “Use desktop theme design” cause it warns about I’ll lose my desktop panels and widgets … anyway, I even had tried it, but nothing changes about my issue.
In attached screenshot (sorry, it seems here can’t upload images) , you can see “Baobab”, “Chrome” and “MS Edge” applications windows with that incredible big borders. They are not clickable or draggable, and always are black color, regardless of theme applied to Plasma.