asciinema.org/app/assets/stylesheets/source-sans-pro.css.erb

@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 300;
  src: local('Source Sans Pro Light'), local('SourceSansPro-Light'), url('<%= asset_path("SourceSansPro-Light.ttf") %>') format('truetype');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 400;
  src: local('Source Sans Pro'), local('SourceSansPro-Regular'), url('<%= asset_path("SourceSansPro-Regular.ttf") %>') format('truetype');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 600;
  src: local('Source Sans Pro Semibold'), local('SourceSansPro-Semibold'), url('<%= asset_path("SourceSansPro-Semibold.ttf") %>') format('truetype');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 700;
  src: local('Source Sans Pro Bold'), local('SourceSansPro-Bold'), url('<%= asset_path("SourceSansPro-Bold.ttf") %>') format('truetype');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: italic;
  font-weight: 400;
  src: local('Source Sans Pro Italic'), local('SourceSansPro-It'), url('<%= asset_path("SourceSansPro-Italic.ttf") %>') format('truetype');
}