Color Fonts

Adobe explaining:

OpenType-SVG is a font format in which an OpenType font has all or just some of its glyphs represented as SVG (scalable vector graphics) artwork. This allows the display of multiple colors and gradients in a single glyph. Because of these features, we also refer to OpenType-SVG fonts as color fonts.

Support so far: Firefox 26+, Edge 38+

But good news, it's progressive enhancement friendly. The Typekit announcement page:

In browsers that lack color font support, …

Color Fonts is a post from CSS-Tricks