Another work-around would be to install the Microsoft Word file Import/Export (Book) plugin (which I developed), which will allow you export either a single chapter or an entire book into Word format. You can then use the style settings in Word to modify the appearance to your preferences quite easily. For example, you can set the Normal paragraph style to be a sans serif font, and all the styles based on this (by default, almost everything except table cells I think) will have the sans serif font applied.
It gets a bit complicated with images though. Although the plugin exports them, you need to run a VBA macro in Word to convert them from Base64 into embedded image format, and at present, Windows Defender thinks the macro is malware, so you need to turn it off to be able to run it.