GENERATE_SOURCEMAP=false does not minifying .css files

I have a React application, and I’ve noticed that when I open Chrome Developer Tools and go to the Sources tab, I can see a folder named static/js. Expanding this folder reveals the entire code of my React project. This seems concerning from a security perspective.

So I went with the GENERATE_SOURCEMAP=false and it works for me for .js files only. I can still see the .css files in the Sources tab in static folder.

build: set "GENERATE_SOURCEMAP=false" && react-scripts build

How can I achieve to minify the css files? Does GENERATE_SOURCEMAP minifes js files only? How can I prevent the source code of my React app from being exposed in this manner? Is there a way to obfuscate or hide the code to enhance security?

Thanks in advance for your help!