Animated Login Form using HTML CSS & JavaScript

1. HTML

<div class="container">
		<header>Login Form</header>
		<form>
			<div class="input-field">
				<input type="text" required>
				<label>Email or Username</label>
			</div>
			<div class="input-field">
				<input class="pswrd" type="password" required>
				<span class="show">SHOW</span>
				<label>Password</label>
			</div>
			<div class="button">
				<div class="inner">
				</div>
				<button>LOGIN</button>
			</div>
		</form>
		<div class="auth">
		Or login with</div>
		<div class="links">
			<div class="facebook">
				<i class="fab fa-facebook-square"><span>Facebook</span></i>
			</div>
			<div class="google">
				<i class="fab fa-google-plus-square"><span>Google</span></i>
			</div>
		</div>
		<div class="signup">
			Not a member? <a href="#">Signup now</a>
		</div>
	</div>

2. CSS

@import url('https://fonts.googleapis.com/css?family=Montserrat:600|Noto+Sans|Open+Sans:400,700&display=swap');
*{
  margin: 0;
  padding: 0;
  border-radius: 5px;
  box-sizing: border-box;
}
body{
  height: 100vh;
  display: flex;
  align-items: center;
  text-align: center;
  font-family: sans-serif;
  justify-content: center;
  background: url(https://devforum.info/DEMO/LoginForm1/bg.jpg);
  background-size: cover;
  background-position: center;
}
.container{
  position: relative;
  width: 400px;
  background: white;
  padding: 60px 40px;
}
header{
  font-size: 40px;
  margin-bottom: 60px;
  font-family: 'Montserrat', sans-serif;
}
.input-field, form .button{
  margin: 25px 0;
  position: relative;
  height: 50px;
  width: 100%;
}
.input-field input{
  height: 100%;
  width: 100%;
  border: 1px solid silver;
  padding-left: 15px;
  outline: none;
  font-size: 19px;
  transition: .4s;
}
input:focus{
  border: 1px solid #1DA1F2;
}
.input-field label, span.show{
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
}
.input-field label{
  left: 15px;
  pointer-events: none;
  color: grey;
  font-size: 18px;
  transition: .4s;
}
span.show{
  right: 20px;
  color: #111;
  font-size: 14px;
  font-weight: bold;
  cursor: pointer;
  user-select: none;
  visibility: hidden;
  font-family: 'Open Sans', sans-serif;
}
input:valid ~ span.show{
  visibility: visible;
}
input:focus ~ label,
input:valid ~ label{
  transform: translateY(-33px);
  background: white;
  font-size: 16px;
  color: #1DA1F2;
}
form .button{
  margin-top: 30px;
  overflow: hidden;
  z-index: 111;
}
.button .inner{
  position: absolute;
  height: 100%;
  width: 300%;
  left: -100%;
  z-index: -1;
  transition: all .4s;
  background: -webkit-linear-gradient(right,#00dbde,#fc00ff,#00dbde,#fc00ff);
}
.button:hover .inner{
  left: 0;
}
.button button{
  width: 100%;
  height: 100%;
  border: none;
  background: none;
  outline: none;
  color: white;
  font-size: 20px;
  cursor: pointer;
  font-family: 'Montserrat', sans-serif;
}
.container .auth{
  margin: 35px 0 20px 0;
  font-size: 19px;
  color: grey;
}
.links{
  display: flex;
  cursor: pointer;
}
.facebook, .google{
  height: 40px;
  width: 100%;
  border: 1px solid silver;
  border-radius: 3px;
  margin: 0 10px;
  transition: .4s;
}
.facebook:hover{
  border: 1px solid #4267B2;
}
.google:hover{
  border: 1px solid #dd4b39;
}
.facebook i, .facebook span{
  color: #4267B2;
}
.google i, .google span{
  color: #dd4b39;
}
.links i{
  font-size: 23px;
  line-height: 40px;
  margin-left: -90px;
}
.links span{
  position: absolute;
  font-size: 17px;
  font-weight: bold;
  padding-left: 8px;
  font-family: 'Open Sans', sans-serif;
}
.signup{
  margin-top: 50px;
  font-family: 'Noto Sans', sans-serif;
}
.signup a{
  color: #3498db;
  text-decoration: none;
}
.signup a:hover{
  text-decoration: underline;
}

3. JAVASCRIPT

/*Chèn Fontawesome dô nghen:  https://kit.fontawesome.com/a076d05399.js*/