_typography.scss

@import url('http://roboto-webfont.googlecode.com/svn/trunk/roboto.all.css'); 

$_gmd-type-styles: (
  display4: (
    font-family: "Roboto light",
    font-size: 8em,
    color: rgba(black, .54),
  ),
  display3: (
    font-family: "Roboto regular",
    font-size: 4em,
    color: rgba(black, .54),
  ),
  display2: (
    font-family: "Roboto regular",
    font-size: 3.21428571em,
    color: rgba(black, .54),
  ),
  display1: (
    font-family: "Roboto regular",
    font-size: 2.42857143em,
    color: rgba(black, .54),
  ),
  headline: (
    font-family: "Roboto regular",
    font-size: 1.71428571em,
    color: rgba(black, .87),
  ),
  title: (
    font-family: "Roboto medium",
    font-size: 1.42857143em,
    color: rgba(black, .87),
  ),
  subhead: (
    font-family: "Roboto regular",
    font-size: 1.14285714em,
    color: rgba(black, .87),
  ),
  body2: (
    font-family: "Roboto medium",
    font-size: 1em,
    color: rgba(black, .87),
  ),
  body1: (
    font-family: "Roboto regular",
    font-size: 1em,
    color: rgba(black, .87),
  ),
  caption: (
    font-family: "Roboto regular",
    font-size: .85714286em,
    color: rgba(black, .54),
  ),
  menu: (
    font-family: "Roboto medium",
    font-size: 1em,
    color: rgba(black, .87),
  ),
  button: (
    font-family: "Roboto medium",
    font-size: 1em,
    text-transform: uppercase,
    color: rgba(black, .87),
  )
);

@mixin gmd-type-style($type) {
  $style: map-get($_gmd-type-styles, $type);
  @each $property, $value in $style {
    #{$property}: $value;
  }
}

// TEST

body {
  @include gmd-type-style(display4);
}