html {
  height: 100%;
}

body {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
  background: linear-gradient(#141e30, #243b55);
}

.login-box {
  position: absolute;
  top: 25%;
  left: 50%;
  width: 80%;
  padding: 1vw;
  transform: translate(-50%, -30%);
  background: rgba(0, 0, 0, .5);
  box-sizing: border-box;
  box-shadow: 0 1.5vw 2.5vw rgba(0, 0, 0, .6);
  border-radius: 2vw;
}

.login-box h1 {
  margin: 0 0 3vw;
  padding: 0;
  color: #b9aefa;
  text-align: center;
}

.login-box h2 {
  margin: 0 0 3vw;
  padding: 0;
  color: #4af7348e;
  text-align: center;
}

.login-box .user-box {
  position: relative;
}

.login-box .user-box input {
  width: 100%;
  padding: 2vw 0;
  font-size: 5vw;
  color: navy;
  margin-bottom: 2vw;
  border: none;
  border-bottom: 1px solid navy;
  outline: none;
  background: transparent;
}

.login-box .user-box label {
  position: absolute;
  top: 0;
  left: 0;
  padding: 2vw 0;
  font-size: 5vw;
  color: #4af7348e;
  pointer-events: none;
  transition: .5s;
}

.login-box .user-box input:focus~label,
.login-box .user-box input:valid~label {
  top: -2vw;
  left: 0;
  color: #03e9f4;
  font-size: 5vw;
}

.login-box form a {
  position: relative;
  display: inline-block;
  padding: 1vw 2vw;
  color: #03e9f4;
  font-size: 5vw;
  text-decoration: none;
  text-transform: uppercase;
  overflow: hidden;
  transition: .5s;
  margin-top: 2vw;
  letter-spacing: 4px
}

.login-box a:hover {
  background: #03e9f4;
  color: #fff;
  border-radius: .5vw;
  box-shadow: 0 0 .5vw #03e9f4,
    0 0 2.5vw #03e9f4,
    0 0 5vw #03e9f4,
    0 0 10vw #03e9f4;
}

.login-box a span {
  position: absolute;
  display: block;
}

.login-box a span:nth-child(1) {
  top: 0;
  left: -5%;
  width: 10%;
  height: 2px;
  background: linear-gradient(90deg, transparent, #03e9f4);
  animation: btn-anim1 2s linear infinite;
}

@keyframes btn-anim1 {
  0% {
    left: -5%;
  }

  50%,
  100% {
    left: 80%;
  }
}

.login-box a span:nth-child(2) {
  top: -5%;
  right: 0;
  width: 2px;
  height: 10%;
  background: linear-gradient(180deg, transparent, #03e9f4);
  animation: btn-anim2 2s linear infinite;
  animation-delay: .25s
}

@keyframes btn-anim2 {
  0% {
    top: -5%;
  }

  50%,
  100% {
    top: 80%;
  }
}

.login-box a span:nth-child(3) {
  bottom: 0;
  right: -5%;
  width: 10%;
  height: 2px;
  background: linear-gradient(270deg, transparent, #03e9f4);
  animation: btn-anim3 2s linear infinite;
  animation-delay: .5s
}

@keyframes btn-anim3 {
  0% {
    right: -5%;
  }

  50%,
  100% {
    right: 80%;
  }
}

.login-box a span:nth-child(4) {
  bottom: -5%;
  left: 0;
  width: 2px;
  height: 10%;
  background: linear-gradient(360deg, transparent, #03e9f4);
  animation: btn-anim4 .5s linear infinite;
  animation-delay: .75s
}

@keyframes btn-anim4 {
  0% {
    bottom: -5%;
  }

  50%,
  100% {
    bottom: 80%;
  }
}