After SSL Plugin CSS not allowed

Hello,

first of all thank you for your nice and very helpful plugin!
However, I switched my homepage to ssl security and I am getting this message now:

[Warning] [blocked] The page at https://zyko.shop/ was not allowed to run insecure content from https://zyko.shop/wp-content/plugins/woo-multi-currency/css/woo-multi-currency.css. (zyko.shop, line 112)

and the previously pretty floating buttons are now just at the very bottom of the page where nobody will find them.

Do you have an idea how Ic could fix this?

Thanks a lot!
Roman

The page I need help with: [log in to see the link]