Making fenced code with language in a Markdown editor “monospace”

Example: affectionate-dan-ypuivs - CodeSandbox

In a Markdown editor with code language highlighting, inline code, indented block code, and fenced code without a language specified would all be in a monospace tag, so the word “hello” would be marked monospace in all of these examples:

`hello`

    hello

\```
hello
\```

(Ignore the backslashes.)

However, if I add a language to fenced code blocks, it no longer becomes monospace and is treated as separate code:

\```html
hello
\```

It makes sense to have this as default, but is there any way to make it so that text in this type of code block has a different theme? I would like it to be treated differently.

The way to add styling to all content in a given language is something like

HighlightStyle.define([], {scope: javascriptLangauge, all: {fontFamily: "monospace"}})

Or, possibly easier, style Markdown code with a variable-width font.