Multi-weight, multi-style @font-face syntax.This example sets up Source Sans Pro in regular, italic, extra light, and semi-bold under 1 font name.

multi-font-face-syntax.css

@font-face {
  font-family: 'Source Sans Pro';
    src: url('assets/fonts/SourceSansPro-Regular.eot');
    src: url('assets/fonts/SourceSansPro-Regular.eot?#iefix') format('embedded-opentype'),
         url('assets/fonts/SourceSansPro-Regular.woff') format('woff'),
         url('assets/fonts/SourceSansPro-Regular.ttf') format('truetype'),
         url('assets/fonts/SourceSansPro-Regular.svg#source_sans_proregular') format('svg');
  font-weight: 400;
  font-style: normal;
}
 
@font-face {
 font-family: 'Source Sans Pro';
    src: url('assets/fonts/SourceSansPro-Italic.eot');
    src: url('assets/fonts/SourceSansPro-Italic.eot?#iefix') format('embedded-opentype'),
         url('assets/fonts/SourceSansPro-Italic.woff') format('woff'),
         url('assets/fonts/SourceSansPro-Italic.ttf') format('truetype'),
         url('assets/fonts/SourceSansPro-Italic.svg#source_sans_proitalic') format('svg');
 font-weight: 400;
 font-style: italic;
}

@font-face {
 font-family: 'Source Sans Pro';
    src: url('assets/fonts/SourceSansPro-ExtraLight.eot');
    src: url('assets/fonts/SourceSansPro-ExtraLight.eot?#iefix') format('embedded-opentype'),
         url('assets/fonts/SourceSansPro-ExtraLight.woff') format('woff'),
         url('assets/fonts/SourceSansPro-ExtraLight.ttf') format('truetype'),
         url('assets/fonts/SourceSansPro-ExtraLight.svg#source_sans_proextralight') format('svg');
 font-weight: 200;
 font-style: normal;
}

@font-face {
 font-family: 'Source Sans Pro';
    src: url('assets/fonts/SourceSansPro-SemiBold.eot');
    src: url('assets/fonts/SourceSansPro-SemiBold.eot?#iefix') format('embedded-opentype'),
         url('assets/fonts/SourceSansPro-SemiBold.woff') format('woff'),
         url('assets/fonts/SourceSansPro-SemiBold.ttf') format('truetype'),
         url('assets/fonts/SourceSansPro-SemiBold.svg#source_sans_prosemibold') format('svg');
 font-weight: 600;
 font-style: normal;
}