How to set up CSP in Safari Extension?

Question

safari

Good day to all!
there is a safari extension
which does the following

@font-face {
  font-family: "jeticon";
  src:url("./fonts/jeticon.eot");
  src:url("./fonts/jeticon.eot?#iefix") format("embedded-opentype"),
    url("./fonts/jeticon.woff") format("woff"),
    url("./fonts/jeticon.ttf") format("truetype"),
    url("./fonts/jeticon.svg#jeticon") format("svg");
  font-weight: normal;
  font-style: normal;
}

and

@import url('https://fonts.googleapis.com/css?family=Open+Sans:300,300i,400,400i,600,600i&subset=cyrillic,cyrillic-ext,greek,greek-ext,latin-ext,vietnamese');

And when I load it, I see this.

How can you solve this issue with safari?