Overleaf/services/web/frontend/fonts/open-sans/open-sans.css

@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 300;
  src: url('OpenSans-Light.woff2') format('woff2');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 400;
  src: url('OpenSans-Regular.woff2') format('woff2');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 600;
  src: url('OpenSans-SemiBold.woff2') format('woff2');
}
@font-face {
  font-family: 'Open Sans';
  font-style: normal;
  font-weight: 700;
  src: url('OpenSans-Bold.woff2') format('woff2');
}