Border radius @mixin

SASS

@mixin border-radius-partial($radius, $part:null) {
  @if ($part) {
    -webkit-border-#{$part}-radius: $radius;
    -moz-border-#{$part}-radius: $radius;
    -ms-border-#{$part}-radius: $radius;
    border-#{$part}-radius: $radius;
  }
  @else {
    -webkit-border-radius: $radius;
    -moz-border-radius: $radius;
    -ms-border-radius: $radius;
    border-radius: $radius;
  }
}

@mixin border-radius($radius, $top-right:null, $bottom-right:null, $bottom-left:null, $top-left:null) {
  @if ($top-right or $bottom-right or $bottom-left or $top-left) {
    @if ($top-right) {
      @include border-radius-partial($radius, 'top-right');
    }
    @if ($bottom-right) {
      @include border-radius-partial($radius, 'bottom-right');
    }
    @if ($bottom-left) {
      @include border-radius-partial($radius, 'bottom-left');
    }
    @if ($top-left) {
      @include border-radius-partial($radius, 'top-left');
    }
  }
  @else {
    @include border-radius-partial($radius);
  }
}