src/scss/layout/_navigation.scss

#nav__top-level {
  background: $black;
  height: 100%;
  position: fixed;
  left: 0;
  top: 0;
  bottom: 0;
  z-index: 99;
  list-style-type: none;
  margin: 0;
  li { margin: 0; }
  .button, button, a {
    background: transparent;
    height: auto;
    border: 0;
    color: $white;
    fill: $white;
    width: 100%;
    padding: 1em;
    display: block;
    text-align: center;
    margin-bottom: 0;
    white-space: normal;
    .nav__icon {
      color: $white;
      max-height: 40px;
      stroke-width: .5;
      margin-bottom: -.5em;
    }
    a {
      margin-bottom: 5px;
    }
    p {
      margin: 0;
      font-size: .9em;
      line-height:1.2rem;
    }

    .nav__icon-help__outer {
      fill: transparent;
      stroke: $white;
      stroke-miterlimit: 10;
      stroke-width: 1px;
    }
    .nav__icon-help__Inner {
      fill: $white;
    }
    &:hover {
      background: $white;
      fill: $black;
      color: $black;
      padding: 1em;
      border-radius: 0;
      .nav__icon-help__outer {
        stroke: $black;
      }
      .nav__icon-help__inner {
        fill: $black;
      }
    }
  }
  .opened {
    background: $white;
    fill: $black;
    color: $black;
  }
}

.nav__second-level {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  z-index: 97;
  display: block;
  background: $white;
  padding: 10px .6em;
  margin: 0;
  list-style-type: none;
  transition: all ease-out 0.5s;
  box-shadow: 0 2px 5px 0 $black;
  &.opened {
    transition: all ease-out .8s;

  }
}