// emboss a box
@mixin box-emboss($opacity, $opacity2){
    box-shadow:white($opacity) 0 1px 0, inset black($opacity2) 0 1px 0;
}

// letterpress
@mixin letterpress($opacity){
    text-shadow:white($opacity) 0 1px 0;
}

// calculate rem font-size
@function calculateRem($size) {
  $remSize: $size / 16px;
  @return $remSize * 1rem;
}
@mixin font-size($size) {
  font-size: $size;
  font-size: calculateRem($size);
}

// border radius
@mixin border-radius($radius) {
  -webkit-border-radius: $radius;
     -moz-border-radius: $radius;
      -ms-border-radius: $radius;
          border-radius: $radius;
}