* {
  margin: 0;
  padding: 0;
  font-family: sans-serif;
}
body {
  display: flex;
  width: 100%;
  height: 100vh;
  /* background: linear-gradient(
    to right,
    #6a82fb,
    #fc5c7d
  ); */
background: linear-gradient(to right, #24243e, #302b63, #0f0c29); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */

  justify-content: center;
  text-align: center;
}
.login-box {
  width: 400px;
  height: 420px;
  padding: 20px;
  border-radius: 20px;
  margin-top: 100px;
  background: #108dc7; /* fallback for old browsers */
  background: -webkit-linear-gradient(
    to right,
    #ef8e38,
    #108dc7
  ); /* Chrome 10-25, Safari 5.1-6 */
  background: linear-gradient(
    to right,
    #ef8e38,
    #108dc7
  ); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */

  box-sizing: border-box;
  box-shadow: 0 15px 25px rgba(0, 0, 0, 0.6);
}
h2 {
  padding: 20px;
  margin: 0 0 30px;
}
.login-box .user-box {
  padding: 20px;
}
.login-box .user-box input {
  border-radius: 3px;
  border: none;
  border-bottom: 1px solid #fff;
  outline: none;
  background: transparent;
  font-size: 16px;
  color: #fff;
  margin-bottom: 30px;
  padding: 10px 0;
}
input::placeholder {
  color: #536976; /* fallback for old browsers */
  color: -webkit-linear-gradient(
    to right,
    #292e49,
    #536976
  ); /* Chrome 10-25, Safari 5.1-6 */
  color: linear-gradient(
    to right,
    #292e49,
    #536976
  ); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
  font-size: 15px;
  font-weight: 100px;
}

/* Button */
.login-box form a {
  position: relative;
  display: inline-block;
  padding: 10px 20px;
  color: #03e9f4;
  font-size: 16px;
  text-decoration: none;
  text-transform: uppercase;
  overflow: hidden;
  transition: 0.5s;
  letter-spacing: 2px;
}
.login-box a:hover {
  background: #f7ff00; /* fallback for old browsers */
  background: -webkit-linear-gradient(
    to right,
    #db36a4,
    #f7ff00
  ); /* Chrome 10-25, Safari 5.1-6 */
  background: linear-gradient(
    to right,
    #db36a4,
    #f7ff00
  ); /* W3C, IE 10+/ Edge, Firefox 16+, Chrome 26+, Opera 12+, Safari 7+ */
  color: #fff;
  border-radius: 5px;
  /* box-shadow: 0 0 5px #03e9f4,
              0 0 25px #03e9f4,
              0 0 50px #03e9f4,
              0 0 100px #03e9f4; */
  box-shadow: 0 0 5px #db36a4, 0 0 25px #db36a4, 0 0 50px #f7ff00,
    0 0 100px #f7ff00;
}
/* span design */
.login-box a span {
  position: absolute;
  display: block;
}
/* child 1 */
.login-box a span:nth-child(1) {
  top: 0;
  left: -100%;
  height: 3px;
  width: 100%;
  background: linear-gradient(90deg, transparent, #db36a4);
  animation: btn-anim1 1s linear infinite;
}
@keyframes btn-anim1 {
  0% {
    left: -100%;
  }
  50%,
  100% {
    left: 100%;
  }
}
/* child 2 */
.login-box a span:nth-child(2) {
  right: 0;
  top: -100%;
  width: 3px;
  height: 100%;
  background: linear-gradient(180deg, transparent, #f7ff00);
  animation: btn-anim2 1s linear infinite;
  animation-delay: 0.25s;
}
@keyframes btn-anim2 {
  0% {
    top: -100%;
  }
  50%,
  100% {
    top: 100%;
  }
}
/* child 3 */
.login-box a span:nth-child(3) {
  bottom: 0;
  right: -100%;
  height: 3px;
  width: 100%;
  background: linear-gradient(270deg, transparent, #db36a4);
  animation: btn-anim3 1s linear infinite;
  animation-delay: 0.5s;
}
@keyframes btn-anim3 {
  0% {
    right: -100%;
  }
  50%,
  100% {
    right: 100%;
  }
}
/* child 4 */
.login-box a span:nth-child(4) {
  left: 0;
  bottom: -100%;
  width: 3px;
  height: 100%;
  background: linear-gradient(270deg, transparent, #f7ff00);
  animation: btn-anim4 1s linear infinite;
  animation-delay: 0.75s;
}
@keyframes btn-anim4 {
  0% {
    bottom: -100%;
  }
  50%,
  100% {
    bottom: 100%;
  }
}