MIME type

If I use the static path directly
```html

```
it works however if I generated the hashFS with a helper

```html

```

```bash
Refused to apply style from 'http://localhost:8080/servers/static/css/site-1630dff5128f31e61ad0a0b14c00d7e23df50237793a9c09d96bf564a8d54883.css' because its MIME type ('text/plain') is not a supported stylesheet MIME type, and strict MIME checking is enabled.
```

Both way use the `hashfs.FileServer` so I'm surprised by the behavior. Any thoughts would helpful.

Start by reproducing the difference between a direct /static/css/site.css URL and the staticPath("css/site.css") URL through hashfs.FileServer. Inspect how the generated hashed path is served and how its MIME type is determined; done means the generated stylesheet is served with a supported stylesheet MIME type, with a regression check if the project has an applicable test entry point.

Written by the indexing model from the issue text.