Source Sans Pro in action on historicengland.org.uk

Under the hood

.header-1 { font-family: "Source Sans Pro", sans-serif; font-size: 50px; font-style: normal; font-weight: 300; letter-spacing: normal; line-height: 55px; text-transform: none; color: #555555; }
.content-1 { font-family: "Source Sans Pro", sans-serif; font-size: 18px; font-style: normal; font-weight: 300; letter-spacing: 0px; line-height: 27px; text-transform: none; color: #577C30; }
.content-2 { font-family: "Source Sans Pro", sans-serif; font-size: 18px; font-style: normal; font-weight: 300; letter-spacing: 0px; line-height: 27px; text-transform: none; color: #333333; }
.content-3 { font-family: "Source Sans Pro", sans-serif; font-size: 18px; font-style: normal; font-weight: 300; letter-spacing: 0px; line-height: 27px; text-transform: none; color: #333333; }