JSFiddle - React, Tailwind, and code Playground

HTML

<input placeholder="Username" type="text" required>
<input placeholder="Password" type="password" required>

CSS

input {
  margin: 40px 25px;
  width: 200px;
  display: block;
  border: none;
  padding: 10px 0;
  border-bottom: solid 1px #1abc9c;
  -webkit-transition: all 0.3s cubic-bezier(0.64, 0.09, 0.08, 1);
  transition: all 0.3s cubic-bezier(0.64, 0.09, 0.08, 1);
  background: -webkit-linear-gradient(top, rgba(255, 255, 255, 0) 96%, #1abc9c 4%);
  background: linear-gradient(to bottom, rgba(255, 255, 255, 0) 96%, #1abc9c 4%);
  background-position: -200px 0;
  background-size: 200px 100%;
  background-repeat: no-repeat;
  color: #0e6252;
}

input:focus, input:valid {
 box-shadow: none;
 outline: none;
 background-position: 0 0;
}

input::-webkit-input-placeholder {
 font-family: 'roboto', sans-serif;
 -webkit-transition: all 0.3s ease-in-out;
 transition: all 0.3s ease-in-out;
}

input:focus::-webkit-input-placeholder, input:valid::-webkit-input-placeholder {
 color: #1abc9c;
 font-size: 11px;
 -webkit-transform: translateY(-20px);
 transform: translateY(-20px);
 visibility: visible !important;
}