Markdown with code block comes out with css data in the code block

Given a file with the following content:
```csharp
var builder = WebApplication.CreateBuilder(args);
```


The rendering is wonky, with css classes coming out in the view:

<img width="838" height="160" alt="Image" src="https://github.com/user-attachments/assets/9fb6916f-fdef-45ee-8e39-14e399f7535b" />
