@font-face {
    font-family: nav;
    src: url('../fonts/Inversionz.otf');
}


.button_container {
  position: absolute;
  top: 50%;
  right: 3%;
  transform: translate(-50%,-50%);
  height: 27px;
  width: 35px;
  cursor: pointer;
  z-index: 99;
  transition: opacity .25s ease;
}
.button_container:hover {
  opacity: .7;
}
.button_container.active .top {
  transform: translateY(11px) translateX(0) rotate(45deg);
  background: white;
}
.button_container.active .middle {
  opacity: 0;
  background: white;
}
.button_container.active .bottom {
  transform: translateY(-11px) translateX(0) rotate(-45deg);
  background: white;
}
.button_container span {
  background: white;
  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-color: rgba(0,0,0,0.8);
   top: 0;
  left: 0;
  width: 100%;
  height: 0%;
  opacity: 0;
  visibility: hidden;
  transition: opacity .35s, visibility .35s, height .35s;
  overflow: hidden;
}
.overlay.open {
  opacity: 1;
  visibility: visible;
  height: 100%;
}
.overlay.open li {
  animation: fadeInRight .5s ease forwards;
  animation-delay: .35s;
}
.overlay.open li:nth-of-type(2) {
  animation-delay: .4s;
}
.overlay.open li:nth-of-type(3) {
  animation-delay: .45s;
}
.overlay.open li:nth-of-type(4) {
  animation-delay: .50s;
}
.overlay nav {
  position: relative;
  height: 83%;
  top: 50%;
  transform: translateY(-50%);
  font-size: 50px;
  font-family: nav;
  text-align: center;
}
.overlay ul {
  list-style: none;
  padding: 0;
  margin: 0 auto;
  display: inline-block;
  position: relative;
  height: 100%;
}
.overlay ul li {
  display: block;
  height: 25%;
  height: calc(100% / 8);
  min-height: 50px;
  position: relative;
  opacity: 0;
}
.overlay ul li a {
  display: block;
  position: relative;
  color: white;
  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%;
  transform: translateX(-50%);
  height: 3px;
  background: #FFF;
  transition: .55s;
}

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

@media screen and (max-width: 450px) {
  .overlay nav{
    font-size: 40px;
  }
}