fonts.css

* { font-family: 'FiraSans'; }

@font-face {
  font-family: 'FiraSans';
  src: url('fonts/FiraSans/FiraSans/FiraSans-Regular.eot');
  src: url('fonts/FiraSans/FiraSans-Regular.eot?#iefix') format('embedded-opentype'),
       url('fonts/FiraSans/FiraSans-Regular.woff') format('woff'),
       url('fonts/FiraSans/FiraSans-Regular.ttf') format('truetype');
  font-weight: normal;
  font-style: normal;
}
@font-face {
  font-family: 'FiraSans';
  src: url('fonts/FiraSans/FiraSans-Light.eot');
  src: url('fonts/FiraSans/FiraSans-Light.eot?#iefix') format('embedded-opentype'),
       url('fonts/FiraSans/FiraSans-Light.woff') format('woff'),
       url('fonts/FiraSans/FiraSans-Light.ttf') format('truetype');
  font-weight: 300;
  font-style: normal;
}
@font-face {
  font-family: 'FiraSans';
  src: url('fonts/FiraSans/FiraSans-Medium.eot');
  src: url('fonts/FiraSans/FiraSans-Medium.eot?#iefix') format('embedded-opentype'),
       url('fonts/FiraSans/FiraSans-Medium.woff') format('woff'),
       url('fonts/FiraSans/FiraSans-Medium.ttf') format('truetype');
  font-weight: 500;
  font-style: normal;
}
@font-face {
  font-family: 'FiraSans';
  src: url('fonts/FiraSans/FiraSans-Bold.eot');
  src: url('fonts/FiraSans/FiraSans-Bold.eot?#iefix') format('embedded-opentype'),
       url('fonts/FiraSans/FiraSans-Bold.woff') format('woff'),
       url('fonts/FiraSans/FiraSans-Bold.ttf') format('truetype');
  font-weight: bold;
  font-style: normal;
}