How To Specify Notebook Font On JupyterLab

I had a question about changing the font on the advanced settings editor for the notebooks.

I successfully installed the Dracula theme that I really love and, now I'm facing a very frustrating issue.

Here are my settings:

Now, when I look at my notebook, I see the expected result:

However, when I change it to the fonts here:

For example:

{
    "codeCellConfig": {
        "autoClosingBrackets": true,
        "fontFamily": "SF Mono",
        "fontSize": 30,
        "lineHeight": null,
        "lineNumbers": false,
        "lineWrap": "off",
        "matchBrackets": true,
        "readOnly": false,
        "insertSpaces": true,
        "tabSize": 4,
        "wordWrapColumn": 80,
        "rulers": [],
        "codeFolding": true,
        "lineWiseCopyCut": true
    },
}

I get this ugly text when VSCode also has when you enter an invalid font: