gitlab-org--gitlab-foss/app/assets/stylesheets/framework/fonts.scss

/* latin-ext */
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 300;
  src: local('Source Sans Pro Light'), local('SourceSansPro-Light'), font-url('SourceSansPro-Light.ttf');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 400;
  src: local('Source Sans Pro'), local('SourceSansPro-Regular'), font-url('SourceSansPro-Regular.ttf');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 600;
  src: local('Source Sans Pro Semibold'), local('SourceSansPro-Semibold'), font-url('SourceSansPro-Semibold.ttf');
}
@font-face {
  font-family: 'Source Sans Pro';
  font-style: normal;
  font-weight: 700;
  src: local('Source Sans Pro Bold'), local('SourceSansPro-Bold'), font-url('SourceSansPro-Bold.ttf');
}