The used font - HKGrotesk is only font-style normal and English language.
If you need other style and language, then:
1. Load this font as OTF from: https://www.fontsquirrel.com/fonts/hk-grotesk
2. Import normal and italic fonts to font generator: https://www.fontsquirrel.com/tools/webfont-generator
3. Setup Expert and setup right info (for Czech language and style Italic look at the attachment)
4. Generate fonts and download zip
5. Unzip fonts, load into folder: templates/ja_atoms/fonts/HKGrotesk and rewrite existing
6. Open style file: templates/ja_atoms/fonts/HKGrotesk/stylesheet.css and add new definition for style italic (see attachment)
7. That is all - final version you can see on https://email.minijoomla.org
