I tested on Linux, Windows and Android but not on MacOS but it should not be OS dependant as the font file ZODIAC.TTF is included in the extension.
Check it by: Tools, Web Developer, Style Editor
Left panel should show 2 files: "style.css" and "inline style cheet"
By clicking on the last one right panel should display:

@font-face {
font-family: "Zodiac";
src: url("../fonts/ZODIAC.TTF");
}
# body { font-family: "Zodiac"}

Also by clicking on the "Console" tab of this same debug page, you can display error messages ...