.border-animation {
  --border-width: 0.1em;
  --animation-speed: 0.5s;
  --color: #ffffff;
  color: var(--color);
  position: relative;
  display: inline-block; 
  line-height: 1em;
  -webkit-transform: scale(1, 0.8);
          transform: scale(1, 0.8);
  border: var(--border-width) solid transparent;
}
.border-animation .border-animation__inner {
  position: relative;
  display: inline-block;
  width: 100%;  
  text-transform: uppercase;
  letter-spacing: 0.05em;
  cursor: pointer;
  padding: 0.2em;
  background: #333;
  z-index: 1;
  border: solid var(--border-width) transparent;
}
.border-animation:before, .border-animation:after {
  content: '';
  position: absolute;
  background: var(--color);
}
.border-animation:focus:before, .border-animation:hover:before {
  -webkit-animation: beforeBorders var(--animation-speed) forwards ease-in-out;
          animation: beforeBorders var(--animation-speed) forwards ease-in-out;
}
.border-animation:focus:after, .border-animation:hover:after {
  -webkit-animation: afterBorders var(--animation-speed) forwards ease-in-out;
          animation: afterBorders var(--animation-speed) forwards ease-in-out;
}
.border-animation:focus, .border-animation:hover {
  -webkit-animation: borderColors var(--animation-speed) steps(1) forwards;
          animation: borderColors var(--animation-speed) steps(1) forwards;
  outline: none;
}
.border-animation:focus .border-animation__inner, .border-animation:hover .border-animation__inner {
  -webkit-animation: background calc(var(--animation-speed) / 5 * 3) forwards ease-in-out;
          animation: background calc(var(--animation-speed) / 5 * 3) forwards ease-in-out;
  -webkit-animation-delay: calc(var(--animation-speed) / 5 * 2);
          animation-delay: calc(var(--animation-speed) / 5 * 2);
}

@-webkit-keyframes beforeBorders {
  0% {
    top: calc(var(--border-width) * -1);
    left: 50%;
    bottom: auto;
    right: auto;
    width: 0;
    height: var(--border-width);
  }
  33% {
    top: calc(var(--border-width) * -1);
    left: calc(var(--border-width) * -1);
    bottom: auto;
    right: auto;
    width: calc(var(--border-width) + 50%);
    height: var(--border-width);
  }
  66% {
    top: calc(var(--border-width) * -1);
    left: calc(var(--border-width) * -1);
    bottom: auto;
    right: auto;
    width: var(--border-width);
    height: calc((var(--border-width) * 2) + 100%);
  }
  100% {
    top: auto;
    left: calc(var(--border-width) * -1);
    bottom: calc(var(--border-width) * -1);
    right: auto;
    width: calc(var(--border-width) + 50%);
    height: calc((var(--border-width) * 2) + 100%);
  }
}

@keyframes beforeBorders {
  0% {
    top: calc(var(--border-width) * -1);
    left: 50%;
    bottom: auto;
    right: auto;
    width: 0;
    height: var(--border-width);
  }
  33% {
    top: calc(var(--border-width) * -1);
    left: calc(var(--border-width) * -1);
    bottom: auto;
    right: auto;
    width: calc(var(--border-width) + 50%);
    height: var(--border-width);
  }
  66% {
    top: calc(var(--border-width) * -1);
    left: calc(var(--border-width) * -1);
    bottom: auto;
    right: auto;
    width: var(--border-width);
    height: calc((var(--border-width) * 2) + 100%);
  }
  100% {
    top: auto;
    left: calc(var(--border-width) * -1);
    bottom: calc(var(--border-width) * -1);
    right: auto;
    width: calc(var(--border-width) + 50%);
    height: calc((var(--border-width) * 2) + 100%);
  }
}
@-webkit-keyframes afterBorders {
  0% {
    top: calc(var(--border-width) * -1);
    left: auto;
    bottom: auto;
    right: 50%;
    width: 0;
    height: var(--border-width);
  }
  33% {
    top: calc(var(--border-width) * -1);
    left: auto;
    bottom: auto;
    right: calc(var(--border-width) * -1);
    width: calc(var(--border-width) + 50%);
    height: var(--border-width);
  }
  66% {
    top: calc(var(--border-width) * -1);
    left: auto;
    bottom: auto;
    right: calc(var(--border-width) * -1);
    width: var(--border-width);
    height: calc((var(--border-width) * 2) + 100%);
  }
  100% {
    top: auto;
    left: auto;
    bottom: calc(var(--border-width) * -1);
    right: calc(var(--border-width) * -1);
    width: calc(var(--border-width) + 50%);
    height: calc((var(--border-width) * 2) + 100%);
  }
}
@keyframes afterBorders {
  0% {
    top: calc(var(--border-width) * -1);
    left: auto;
    bottom: auto;
    right: 50%;
    width: 0;
    height: var(--border-width);
  }
  33% {
    top: calc(var(--border-width) * -1);
    left: auto;
    bottom: auto;
    right: calc(var(--border-width) * -1);
    width: calc(var(--border-width) + 50%);
    height: var(--border-width);
  }
  66% {
    top: calc(var(--border-width) * -1);
    left: auto;
    bottom: auto;
    right: calc(var(--border-width) * -1);
    width: var(--border-width);
    height: calc((var(--border-width) * 2) + 100%);
  }
  100% {
    top: auto;
    left: auto;
    bottom: calc(var(--border-width) * -1);
    right: calc(var(--border-width) * -1);
    width: calc(var(--border-width) + 50%);
    height: calc((var(--border-width) * 2) + 100%);
  }
}
@-webkit-keyframes borderColors {
  0% {
    border-top-color: transparent;
    border-right-color: transparent;
    border-bottom-color: transparent;
    border-left-color: transparent;
  }
  33% {
    border-top-color: var(--color);
    border-right-color: transparent;
    border-bottom-color: transparent;
    border-left-color: transparent;
  }
  66% {
    border-top-color: var(--color);
    border-right-color: var(--color);
    border-bottom-color: transparent;
    border-left-color: var(--color);
  }
  100% {
    border-top-color: var(--color);
    border-right-color: var(--color);
    border-bottom-color: var(--color);
    border-left-color: var(--color);
  }
}
@keyframes borderColors {
  0% {
    border-top-color: transparent;
    border-right-color: transparent;
    border-bottom-color: transparent;
    border-left-color: transparent;
  }
  33% {
    border-top-color: var(--color);
    border-right-color: transparent;
    border-bottom-color: transparent;
    border-left-color: transparent;
  }
  66% {
    border-top-color: var(--color);
    border-right-color: var(--color);
    border-bottom-color: transparent;
    border-left-color: var(--color);
  }
  100% {
    border-top-color: var(--color);
    border-right-color: var(--color);
    border-bottom-color: var(--color);
    border-left-color: var(--color);
  }
}
@-webkit-keyframes background {
  to {
    background: #555;
    text-shadow: 0 0.1em 0.1em #111;
  }
}
@keyframes background {
  to {
    background: #555;
    text-shadow: 0 0.1em 0.1em #111;
  }
}
@media (min-width: 850px) {
  body {
    justify-content: center;
  }
}
@media (min-width: 1200px) {
  .border-animation {
    font-size: 6em;
    line-height: 1em;
  }
}