.button_container { float:right;
  position:relative;
  height: 27px;
  width: 35px;
  cursor: pointer;
  z-index: 12;
  transition: opacity .25s ease;
}
.button_container:hover {
  opacity: .7;
}
.button_container.active .top {
  -webkit-transform: translateY(11px) translateX(0) rotate(45deg);
          transform: translateY(11px) translateX(0) rotate(45deg);
  background: #FFF;
}
.button_container.active .middle {
  opacity: 0;
  background: #FFF;
}
.button_container.active .bottom {
  -webkit-transform: translateY(-11px) translateX(0) rotate(-45deg);
          transform: translateY(-11px) translateX(0) rotate(-45deg);
  background: #FFF;
}
.button_container span {
  background:#212121;
  border: none;
  height: 5px;
  width: 100%;
  position: absolute;
  top: 0;
  left: 0;
  transition: all .35s ease;
  cursor: pointer;
}
.button_container span:nth-of-type(2) {
  top: 11px;
}
.button_container span:nth-of-type(3) {
  top: 22px;
}

.overlay {
  position: fixed;
  background: #6b6c6e;
  top: 0;
  left: 0;
  width: 100%;
  height: 0%;
  opacity: 0;
  visibility: hidden;
  transition: opacity .35s, visibility .35s, height .35s;
  overflow: hidden; z-index: 12;
}
.overlay.open {
  opacity: .9;
  visibility: visible;
  height: 100%;
}
.overlay.open li {
  -webkit-animation: fadeInRight .5s ease forwards;
          animation: fadeInRight .5s ease forwards;
  -webkit-animation-delay: .35s;
          animation-delay: .35s;
}
.overlay.open li:nth-of-type(2) {
  -webkit-animation-delay: .4s;
          animation-delay: .4s;
}
.overlay.open li:nth-of-type(3) {
  -webkit-animation-delay: .45s;
          animation-delay: .45s;
}
.overlay.open li:nth-of-type(4) {
  -webkit-animation-delay: .50s;
          animation-delay: .50s;
}
.overlay.open li:nth-of-type(5) {
  -webkit-animation-delay: .55s;
          animation-delay: .55s;
}
.overlay.open li:nth-of-type(6) {
  -webkit-animation-delay: .60s;
          animation-delay: .60s;
}
.overlay.open li:nth-of-type(7) {
  -webkit-animation-delay: .65s;
          animation-delay: .65s;
}
.overlay.open li:nth-of-type(8) {
  -webkit-animation-delay: .70s;
          animation-delay: .70s;
}
.overlay nav {
  position: relative;
  height: 70%;
  top: 50%;
  -webkit-transform: translateY(-50%);
          transform: translateY(-50%);
  font-size: 30px; 
  font-weight: 400;
  text-align: center;
}
.overlay ul {
  list-style: none;
  padding:20px 0;
  margin: 0 auto;
  display:block;
  position: relative; width:80%;
}
.overlay ul li {
  display: block;
  position: relative;
  opacity: 0; text-align:left
}
.overlay ul li a {
  display: block;
  position: relative;
  color: #FFF;
  text-decoration: none;
  overflow: hidden;
}
.overlay ul li a:hover:after, .overlay ul li a:focus:after, .overlay ul li a:active:after {
  width: 100%;
}
.overlay ul li a:after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 0%;
  -webkit-transform: translateX(-50%);
          transform: translateX(-50%);
  height: 3px;
  background: #FFF;
  transition: .35s;
}

@-webkit-keyframes fadeInRight {
  0% {
    opacity: 0;
    left: 20%;
  }
  100% {
    opacity: 1;
    left: 0;
  }
}

@keyframes fadeInRight {
  0% {
    opacity: 0;
    left: 20%;
  }
  100% {
    opacity: 1;
    left: 0;
  }
}

.bottom-overlay-menu { position:absolute; bottom:0; left:0; width:100%; display:flex; padding:0 20px 20px 20px; }
.bottom-overlay-menu>div { flex:1; padding:0 5px; }
.bottom-overlay-menu a { color:#ffffff; display:flex; width:100%; height:100%; align-self: center; text-align:center; justify-content: center; align-items: center; background:rgba(0,0,0,0.2); font-size:13px; line-height:1; padding:12px 5px; }
.overlay .button_container { margin:20px 15px 0 0 }