Simple Subscribe changes font to initial for WP site

When I activate the Simple Subscribe plugin, the theme’s font that I chose (Didact Gothic) was ignored, and the “initial” font was applied, not only to the SUBSCRIBE form from Simple Subscribe, but to the whole site. Upon deactivating the plugin, the theme’s font was used. I tried MANY overrides, but nothing works. Any ideas why this would happen? The theme being used is the Multi-purpose Business Theme by Dixit.