Avenir with Avenir Demi in action on paste.fiftythree.com

.header-1 { font-family: "Avenir Demi", Helvetica, sans-serif; font-size: 64px; font-style: normal; font-weight: bold; letter-spacing: normal; line-height: 0px; text-transform: none; color: #4E45C7; }
.content-1 { font-family: "Avenir Regular", Helvetica, sans-serif; font-size: 36px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 0px; text-transform: none; color: #A99390; }
Avenir is available from Fonts.com, Fontshop and MyFonts.
Found by @mikesten on 18 Apr 2017.

Avenir with Avenir Demi