Josefin Sans in Customizr rendering ugly on Windows

Hi,

I have some design questions. I use Josefin Sans in Customizr Pro (via Google Webfonts) for my site at https://wohnprojekt-hasendorf.at/ (right now I quickly changed to Open Sans in the body but you can still see headings etc. in Josefin Sans).

The font looks beautiful on Mac machines in FF, Chrome, and Safari (and I think Linux, too, but have not checked recently), however on Windows machines the font looks veeeeery ugly in all browser I tested (FF, Chrome, IE). I have done a little and there seems to be a general problem with Josefin Sans via Google Webfonts, I am far from being a web developer though so I do not really understand the issue.

Any advice? Thanks in advance!