eCSStender.font-face.js-example-final.css

@font-face {
  font-family: 'Comfortaa';
  font-weight: normal;
  src: url('fonts/Comfortaa_Regular.eot');
  src: local('Comfortaa'),
       url('fonts/Comfortaa_Regular.ttf') format('truetype'),
       url('fonts/Comfortaa_Regular.otf') format('opentype'),
       url('fonts/Comfortaa_Regular.svg#mysvgid') format('svg');
}

eCSStender.font-face.js-example.css

@font-face {
  font-family: 'Comfortaa';
  font-weight: normal;
  src: url('fonts/Comfortaa_Regular');
}

extensions.js

eCSStender.addMethod('svg_id','mysvgid');