Add a style that overrides font with "inherit" for certain books
BookFusion parses and includes Epub styles on their cloud reader.
This means sometimes you change the font and the book's font doesn't change.
The script in this version works to inject a style at the book level (iframe).
The style can then be updated to "inherit" properties from BF's CSS rather than the book's internal CSS.
It's likely you'll have to update the CSS injected to get the expected result, but this gets safely around injecting a style into the book's iFrame.
