Open Sans in action on recruitee.com

.header-1 { font-family: 'Open Sans', sans-serif; font-size: 46.4000015258789px; font-style: normal; font-weight: 300; letter-spacing: normal; line-height: 51.0400009155273px; text-transform: uppercase; color: #FFFFFF; }
.header-2 { font-family: 'Open Sans', sans-serif; font-size: 19.2000007629395px; font-style: italic; font-weight: normal; letter-spacing: normal; line-height: 27.4285736083984px; text-transform: none; color: #D8E3E7; }
.header-3 { font-family: 'Open Sans', sans-serif; font-size: 13px; font-style: normal; font-weight: 600; letter-spacing: normal; line-height: 18.5714302062988px; text-transform: uppercase; color: #FFFFFF; }
.header-4 { font-family: 'Open Sans', sans-serif; font-size: 13px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 18.5714302062988px; text-transform: none; color: #AFB6BA; }
Open Sans is available from Font Squirrel, Google Web Fonts, MyFonts and Typekit.
Found by @mikesten on 17 Aug 2015.

Liked by:
@mikesten @scottltaylor

Open Sans