Source Sans Pro in action on penlink.com

.header-1 { font-family: "Source Sans Pro", sans-serif; font-size: 28px; font-style: normal; font-weight: bold; letter-spacing: 3.5px; line-height: 49px; text-transform: uppercase; color: #002A48; }
.header-2 { font-family: "Source Sans Pro", sans-serif; font-size: 23.3333px; font-style: normal; font-weight: bold; letter-spacing: 2.91667px; line-height: 40.8333px; text-transform: uppercase; color: #002A48; }
.content-1 { font-family: "Source Sans Pro", sans-serif; font-size: 18.6667px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 32.6667px; text-transform: none; color: #6E6E6E; }
Source Sans Pro is available from Font Squirrel, Google Web Fonts and Typekit.

Try this combination out in Pair and Compare.
Found by @mikesten on 17 Feb 2017.

Liked by:
@mikesten @Jimmy_Franko

Source Sans Pro