I ran into this exact issue where .css files were being served with the text/plain content type, and the browser was refusing to apply the styles.

I went through a long list of troubleshooting steps:

• Made sure the mime.types file was included in my Nginx config

• Verified that .css was correctly mapped to text/css

• Tried different location blocks

• Double-checked the file paths

• Even reinstalled Nginx at some point

Still, no luck — Chrome kept showing Content-Type: text/plain in the Network tab, and the styles just wouldn't apply.

After some frustration, I noticed that the network request in Chrome had been cached, and the cached response had the wrong content type. Here's what worked:

I disabled caching in Chrome DevTools (Network tab → "Disable cache"), refreshed the page — and suddenly the CSS was loading correctly with the right text/css content type.

So in my case, it was a caching issue, and all the correct configurations were being ignored because the browser was holding onto an old, incorrect response.