Ojs css files on a server

Hello Team. I would like to reach css files of an ojs journal web site on the server. I easily find them locally.When I log in by FTP I find some css files, but when I modify them there is no change on the web pages. What is the path to the suitable files?

The recommended way to manage CSS it to upload a Site or Journal specific CSS file with the styles you want.
User Home → Site Administrator → Site Settings → Site Style Sheet
User Home → Journal Manager → Setup → The Look → Journal style sheet

Editing the existing stylesheets (such as ojs/styles at ojs-stable-2_4_7 · pkp/ojs · GitHub) directly is not recommended, but should be possible. If you do so, be sure to perform a hard refresh in your browser, as CSS files are typically cached.

Thanks ctgraham for the quick answer.
I thought there were another recommended way to make it directly on the server by modifying the css files as can be done locally (for example by modifying www\ojs\plugins\themes\choosenstyle.css).
I’ve tried it your way. It works.
Thanks a lot ctgraham.