@mixin triangle($size, $color, $direction) {

$width: nth($size, 1);
$height: nth($size, length($size));
$foreground-color: nth($color, 1);
$background-color: if(length($color) == 2, nth($color, 2), transparent);
height: 0;
width: 0;

@if ($direction == up) or ($direction == down) or ($direction == right) or ($direction == left) {
  $width: $width / 2;
  $height: if(length($size) > 1, $height, $height/2);

  @if $direction == up {
    border-bottom: $height solid $foreground-color;
    border-left: $width solid $background-color;
    border-right: $width solid $background-color;
  } @else if $direction == right {
    border-bottom: $width solid $background-color;
    border-left: $height solid $foreground-color;
    border-top: $width solid $background-color;
  } @else if $direction == down {
    border-left: $width solid $background-color;
    border-right: $width solid $background-color;
    border-top: $height solid $foreground-color;
  } @else if $direction == left {
    border-bottom: $width solid $background-color;
    border-right: $height solid $foreground-color;
    border-top: $width solid $background-color;
  }
} @else if ($direction == up-right) or ($direction == up-left) {
  border-top: $height solid $foreground-color;

  @if $direction == up-right {
    border-left:  $width solid $background-color;
  } @else if $direction == up-left {
    border-right: $width solid $background-color;
  }
} @else if ($direction == down-right) or ($direction == down-left) {
  border-bottom: $height solid $foreground-color;

  @if $direction == down-right {
    border-left:  $width solid $background-color;
  } @else if $direction == down-left {
    border-right: $width solid $background-color;
  }
} @else if ($direction == inset-up) {
  border-color: $background-color $background-color $foreground-color;
  border-style: solid;
  border-width: $height $width;
} @else if ($direction == inset-down) {
  border-color: $foreground-color $background-color $background-color;
  border-style: solid;
  border-width: $height $width;
} @else if ($direction == inset-right) {
  border-color: $background-color $background-color $background-color $foreground-color;
  border-style: solid;
  border-width: $width $height;
} @else if ($direction == inset-left) {
  border-color: $background-color $foreground-color $background-color $background-color;
  border-style: solid;
  border-width: $width $height;
}

}