Example: "Cat Dog Fox"

Excel: Cat.FontStlye = Bold; a.Fontstyle = Bold; c.Fontstyle = Bold; " ".Fontstyle = Regular; D.Fontstyle = BoldItalic; o.Fontstyle = BoldItalic; etc for each character

By default, each new character's Font Object inherits the fontstyle of the preceding character. A Fontstyle 'ends' when a new FontStyle is initiated

Cell.FontStyles provides the default character Fontstyle

Html: <b>Cat <i>Cat</i></b> Dog
Font tags Encapsulate Strings, Encapsulated Tags are additive. A Font 'ends' when the closing Tag is presented.

Encapsulating each character is allowed, <b>C</b><b>a</b><b>t</b> <b><i>D</i></b><b><i>o</i></b><b><i>g</i></b>, etc, and HTMLTidy should clean it up. I would start and end the HTM string(entire cell) with the Tag for the Cell's FontStyle

Personally, I would save all output to a *.htm file, (a basic text file that starts with "<html><body>" & NewLine + results,) and feed that to HTMLTidy.