Override page fonts but allow exceptions

It is great that Firefox allows one to choose preferred fonts for rendering web pages.

However, more and more web pages use special characters from special fonts to realise UI elements such as arrows, question mark icons, etc.

Ticking "Allow pages to choose their own fonts, instead of your selections above" in the Firefox settings will result in the correct rendering of those UI elements but obviously also respects the web page's font choice for normal text.

It would be idea if one could specify one's preferred font for normal text, while allowing special fonts to be used on the page. This could be realised in various ways:

1. Allow the user to specify a list of font exceptions, i.e., fonts that will not be replaced by the user preferred font choice. Typical examples are "Symbol", "Wingdings", etc.

2. Allow the user to specify fonts that should be replaced by the user's preferred font choice. Typical examples are "Garamond", "Times", etc.

3. Have a fixed set of special fonts that will not be replaced by the user's preferred font choice.

I have no strong preference for any of the above alternatives.