$height_line: 2px;

.burger {
  width: 100%;
  height: 100%;
  position: relative;
  transition: 0.5s;
  cursor: pointer;

  p {
    width: 100%;
    height: $height_line;
    display: block;
    background-color: $gray-dark;
    position: absolute;
    transition: .5s;

    &:nth-child(1) {
      top: 0;
    }

    &:nth-child(2) {
      margin-top: -$height_line/2;
      top: 50%;
    }

    &:nth-child(3) {
      bottom: 0;
    }
  }

  &--open {
    p {
      &:nth-child(1) {
        transform-origin: 0 100%;
        transform: rotate(40deg);
      }

      &:nth-child(2) {
        opacity: 0;
        transition: .2s;
      }

      &:nth-child(3) {
        transform-origin: 0 0;
        transform: rotate(-40deg);
      }
    }
  }

  @include respond-to('medium') {

  }
}