JSFiddle - React, Tailwind, and code Playground

by pimur

HTML

<div class="form">
  <input type="text" name="city" id="city" required>
  <label for="city">Город</label>
</div>

CSS

.form {
  position: relative;
  background: #ddd;
  padding: 20px 10px;
  max-width: 200px;
}

.form label {
  font-size: 10px;
  position: absolute;
  top: 50%;
  left: 20px;
  -webkit-transform: translateY(-150%);
  transform: translateY(-150%);
  -webkit-transition: all .7s ease 0s;
  transition: all .7s ease 0s;
  z-index: 1;
}

.form input {
  padding: 10px;
  width: calc(100% - 20px);
  background: transparent;
  border: 1px solid #ccc;
  border-radius: 5px;
}

.form input:invalid+label {
  font-size: 15.38462px;
  position: absolute;
  top: 50%;
  -webkit-transform: translateY(-50%);
  transform: translateY(-50%);
}

.form input:focus+label {
  font-size: 10px;
  -webkit-transform: translateY(-150%);
  transform: translateY(-150%);
}