Fix bold fonts in Safari

[fateeand]

In Safari, all bold fonts are displayed ugly.
The best way how to fix it has to be investigated.

Safari:

Chrome:

[fateeand]

The issue is that we are importing only SourceSansPro-Regular font, which doesn't contain bold style variation and the browsers are synthesizing it in their own way.

https://developer.mozilla.org/en-US/docs/Web/CSS/font-synthesis
https://fontsource.org/fonts/source-sans-pro
https://www.cdnfonts.com/source-sans-pro.font