Markdown preview code block font doesn't follow editor.fontFamily setting

[yume-chan]

Describe the bug

VSCode built in themes uses font-family: var(--vscode-editor-font-family) for code blocks in Markdown preview, which refers to the editor.fontFamily setting and that's what the editor uses.

But this extension's style overrided it to Menlo, which doesn't support font ligatures.

To Reproduce
Steps to reproduce the behavior:

1. Set editor.fontFamily to some font you like
2. Open a Markdown file containing code blocks
3. Open Preview

Expected behavior
Code blocks in Markdown preview uses the same font as editor.fontFamily

Screenshots & Example Code

With "editor.fontFamily": "\"Cascadia Code\""

Code:

```
!=
```

Dark+ theme:

One Dark Pro theme:

Desktop (please complete the following information):

• OS: macOS 12.1
• VSCODE Version: 1.63.2
• Theme version: 3.13.10

[Binaryify]

plz check v3.13.11~

[kossa]

Alright it works fine

[yume-chan]

Fix verified.