@mixin overshoot($p, $t:normal, $c:$selected_bg_color) {
//
// overshoot
//
// $p: position
// $t: type
// $c: base color
//
// possible $p values:
// top, bottom, right, left
//
// possible $t values:
// normal, backdrop
//

  $_small_gradient_length: 3%;
  $_big_gradient_length: 50%;

  $_small_gradient_size: 100% $_small_gradient_length;
  $_big_gradient_size: 100% $_big_gradient_length;

  @if $p==right or $p==left {
    $_small_gradient_size: $_small_gradient_length 100%;
    $_big_gradient_size: $_big_gradient_length 100%;
  }

  $_small_gradient_color: $c;
  $_big_gradient_color: transparentize($c, 0.93);

  @if $c==$fg_color {
    $_small_gradient_color: darken($borders_color, 10%);
    $_big_gradient_color: transparentize($fg_color, 0.93);

    @if $t==backdrop { $_small_gradient_color: $backdrop_borders_color; }
  }

  $_small_gradient: radial-gradient(farthest-side at $p,
                                    $_small_gradient_color 85%,
                                    transparentize($_small_gradient_color, 1));

  $_big_gradient: radial-gradient(farthest-side at $p,
                                  $_big_gradient_color,
                                  transparentize($_big_gradient_color, 1));

  @if $t==normal {
    background-image: $_small_gradient, $_big_gradient;
    background-size: $_small_gradient_size, $_big_gradient_size;
  }

  @else if $t==backdrop {
    background-image: $_small_gradient;
    background-size: $_small_gradient_size;
  }

  background-repeat: no-repeat;
  background-position: $p;

  background-color: transparent; // reset some properties to be sure to not inherit them somehow
  border: none;                  //
  box-shadow: none;              //
}