//
// Absolute
//

@mixin absolute($top: null, $right: null, $bottom: null, $left: null) {
  position: absolute;
  @if $top != null {
    top: $top;
  }
  @if $right != null {
    right: $right;
  }
  @if $bottom != null {
    bottom: $bottom;
  }
  @if $left != null {
    left: $left;
  }
}
// ex.) @include absolute(0,0,0,0); @include absolute($top: 0,$bottom: 0);
// output.) position: absolute;top: 0;right: 0;bottom: 0;left: 0; position: absolute; top: 0; bottom: 0;


//
// Fixed
//

@mixin fixed($top: null, $right: null, $bottom: null, $left: null) {
  position: fixed;
  @if $top != null {
    top: $top;
  }
  @if $right != null {
    right: $right;
  }
  @if $bottom != null {
    bottom: $bottom;
  }
  @if $left != null {
    left: $left;
  }
}