header {
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  font-size: 18px;
  height: 100vh;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  overflow: hidden;
  position: relative;
  text-align: center;
  -webkit-transform-style: preserve-3d;
          transform-style: preserve-3d;

  -webkit-perspective: 100px;

          perspective: 100px;
}

header:before {
  -webkit-animation: fade-slide-down 2s .5s cubic-bezier(0, 0.5, 0, 1) forwards;
          animation: fade-slide-down 2s .5s cubic-bezier(0, 0.5, 0, 1) forwards;
  background: -webkit-linear-gradient(top, rgba(0,0,0,0), rgba(0,0,0,.8)),
              url(../images/background.gif) no-repeat bottom;
  background: linear-gradient(to bottom, rgba(0,0,0,0), rgba(0,0,0,.8)),
              url(../images/background.gif) no-repeat bottom;
  background-size: cover;
    bottom: 0;
  content: "";
    left: 0;
  opacity: 0;
  position: absolute;
    right: 0;
    top: 0;
  z-index: -1;
}

header:after {
  -webkit-animation: rotate-up .5s .5s cubic-bezier(0, 0.5, 0, 1) forwards;
          animation: rotate-up .5s .5s cubic-bezier(0, 0.5, 0, 1) forwards;
  background: #202020;
  content: "";
  height: 40rem;
  left: -5%;
  position: absolute;
    right: -5%;
    top: 90%;
  -webkit-transform-origin: 0 0;
          transform-origin: 0 0;
  z-index: 0;
}

.header-title, .header-subtitle {
  color: #fff;
}

.header-subtitle {
  margin-bottom: 5rem;
  text-transform: uppercase;
}

.header-button {
  position: relative;
  -webkit-transform: translateZ(.1px);
          transform: translateZ(.1px);
  z-index: 10;
}

.animate-pop-in {
  -webkit-animation: pop-in .6s cubic-bezier(0, 0.9, 0.3, 1.2) forwards;
          animation: pop-in .6s cubic-bezier(0, 0.9, 0.3, 1.2) forwards;
  opacity: 0;
}

.header-title {
  -webkit-animation-delay: .8s;
          animation-delay: .8s;
}

.header-subtitle {
  -webkit-animation-delay: 1s;
          animation-delay: 1s;
}

.header-button {
  -webkit-animation-delay: 1.1s;
          animation-delay: 1.1s;
}

.header-down-arrow {
  -webkit-animation: pulse 2s 3s ease-out infinite;
          animation: pulse 2s 3s ease-out infinite;
    bottom: 4vh;
    left: 0;
  position: absolute;
    right: 0;
  text-align: center;
  z-index: 10;
}

.header-down-arrow img {
  -webkit-animation: fade-slide-up 1s 1s ease-out forwards;
          animation: fade-slide-up 1s 1s ease-out forwards;
  opacity: 0;
}

/* Animations */

@-webkit-keyframes fade-slide-down {
  0% {
    opacity: 0;
    -webkit-transform: translateY(-4rem);
            transform: translateY(-4rem);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@keyframes fade-slide-down {
  0% {
    opacity: 0;
    -webkit-transform: translateY(-4rem);
            transform: translateY(-4rem);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@-webkit-keyframes fade-slide-up {
  0% {
    opacity: 0;
    -webkit-transform: translateY(4rem);
            transform: translateY(4rem);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@keyframes fade-slide-up {
  0% {
    opacity: 0;
    -webkit-transform: translateY(4rem);
            transform: translateY(4rem);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@-webkit-keyframes pop-in {
  0% {
    opacity: 0;
    -webkit-transform: translateY(-4rem) scale(.8);
            transform: translateY(-4rem) scale(.8);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@keyframes pop-in {
  0% {
    opacity: 0;
    -webkit-transform: translateY(-4rem) scale(.8);
            transform: translateY(-4rem) scale(.8);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@-webkit-keyframes pulse {
  0% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
  50% {
    opacity: .8;
    -webkit-transform: scale(.8);
            transform: scale(.8);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@keyframes pulse {
  0% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
  50% {
    opacity: .8;
    -webkit-transform: scale(.8);
            transform: scale(.8);
  }
  100% {
    opacity: 1;
    -webkit-transform: none;
            transform: none;
  }
}

@-webkit-keyframes rotate-up {
  100% {
    -webkit-transform: rotateZ(-4deg);
            transform: rotateZ(-4deg);
  }
}

@keyframes rotate-up {
  100% {
    -webkit-transform: rotateZ(-4deg);
            transform: rotateZ(-4deg);
  }
}