.overlay {
  @include opacity(0);
  background-color: $color__brand--black;
  height: 0;
  left: 0;
  position: absolute;
  top: 0;
  transition: opacity .3s, height 0 .3s;
  width: 100%;
  z-index: $z-overlay;
}

.overlay--active {
  @include opacity(.3);
  height: 100%;
  transition: opacity .3s, height 0;
  visibility: visible;
}

.overlay--nav {
  height: 100vh;
  width: 100vw;
}