[Bug]: code highlighting is hard to read

[hardfist]

```sh{4}
  asset-demo
  |- package.json
  |- package-lock.json
  |- speedy.config.ts
  |- /dist
    |- bundle.js
    |- index.html
  |- /src
+   |- style.css
    |- index.js
  |- /node_modules
```

generates