Source Sans Pro with Work Sans in action on relonch.com

.header-1 { font-family: "Work Sans", Arial, sans-serif; font-size: 45px; font-style: normal; font-weight: 300; letter-spacing: normal; line-height: 50px; text-transform: none; color: #43484F; }
.content-1 { font-family: "Source Sans Pro", Arial, sans-serif; font-size: 20px; font-style: normal; font-weight: 300; letter-spacing: normal; line-height: 27px; text-transform: none; color: #43484F; }
.content-2 { font-family: "Work Sans", Arial, sans-serif; font-size: 14px; font-style: normal; font-weight: 600; letter-spacing: normal; line-height: 33px; text-transform: uppercase; color: #FFFFFF; background-color: #43484F; }
.content-3 { font-family: "Work Sans", Arial, sans-serif; font-size: 18px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 23px; text-transform: uppercase; color: #43484F; }
Source Sans Pro is available from Font Squirrel, Google Web Fonts and Typekit.

Work Sans is available from Font Squirrel and Google Web Fonts.

Try this combination out in Pair and Compare.
Found by @mikesten on 20 Sep 2017.

Liked by:
@mikesten @cruzmarycruz @DerienBrown @Joshua_D_ @gtfemy @tim_j_evans @lolidepablo @jfcomartinez18

Source Sans Pro with Work Sans