@font-face {
    font-family: "CircularAirPro-Book";
    src: url("custom.eot");
    src: url("custom.eot?#iefix") format("embedded-opentype"),
         url("custom.woff") format("woff"),
         url("custom.ttf") format("truetype"),
         url("custom.svg#CircularAirPro-Book") format("svg");
    font-weight: normal;
}