in action on semplicelabs.com
.header-1 {
font-family: 'MillerDisplay Light', Georgia, serif;
font-size: 55px;
font-style: normal;
font-weight: normal;
letter-spacing: normal;
line-height: 55px;
text-transform: none;
color: #000000;
}
.content-1 {
font-family: AvenirNextLTW01-Regular, Arial, sans-serif;
font-size: 20px;
font-style: normal;
font-weight: normal;
letter-spacing: normal;
line-height: 28px;
text-transform: none;
color: #5E5E5E;
}
Avenir Next is available from Fonts.com and MyFonts.
Miller Display is available from Webtype.
Found by @mikesten on 27 Apr 2016.