Replacing the "style.css" file?
I would like to replace the default style.css file by the one I copied to "themes/mytheme/wpforo/style.css"
I assumed this was possible, but it doesn't seem to pick up on it automatically. Did I copy it in the wrong folder, or does it not automatically overwrite like php files do?
And how do I make it overwrite the default style.css located in "plugins/wpforo/wpf-themes/classic/style.css"?
I'm sorry but wpForo only supports theme php file overwriting, you can't do the same with CSS files. We'll add this in our to-do list and make it available as soon as possible. Currently you have no option to do this, you should add custom CSS in Forums > Settings > Style admin page or edit wpForo style.css in plugin folder.