hamburger.scss

// Mobile navigation toggle button
@mixin hamburger-icon($width: 40px,
                      $height: 4px,
                      $gap: 5px,
                      $color: #fff,
                      $top: 0,
                      $left: 0) {

  position: relative;
  display: block;
  width: $width;
  height: (($height * 3) + ($gap * 2));

  &:before {
    box-shadow:
      0 ($height + $gap) 0 0 $color,
      0 (($height * 2) + ($gap * 2)) 0 0 $color
    ;
    background: $color;
    content: "";
    position: absolute;
    top: $top;
    left: $left;
    width: $width;
    height: $height;
  }
}