Progressive fallback floating labels

A 'floating label' effect that requires no JS and is progressive enhancement

by Sora2455

HTML

<fieldset>
<legend>
Floating labels example (no-JS)
</legend>
<label class="floating-label">
  <input type="text" placeholder=" ">
  <span>Username</span>
</label>
<label class="floating-label">
  <input type="Password" placeholder=" ">
  <span>Password</span>
</label>
</fieldset>
<p>
Inspired by Bootstrap's <a href="https://getbootstrap.com/docs/4.0/examples/floating-labels/">floating labels</a>.
</p>

SCSS

*, ::after, ::before {
    box-sizing: border-box;
}

label.floating-label {
  display: block;
  position: relative;
  height: 2.2em;
  margin-bottom: 1em;
}

label.floating-label input {
  font-size: 1em;
  height: 2.2em;
  padding-top: 0.7em;
  line-height: 1.5;
  color: #495057;
  background-color: #fff;
  background-clip: padding-box;
  border: 1px solid #ced4da;
  border-radius: 0.25rem;
  transition: border-color 0.15s ease-in-out,box-shadow 0.15s ease-in-out;
}

label.floating-label input:focus {
  color: #495057;
  background-color: #fff;
  border-color: #80bdff;
  outline: 0;
  box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
}

label.floating-label input + span {
  position: absolute;
  top: 0em;
  left: 0;
  display: block;
  width: 100%;
  font-size: 0.66em;
  line-height: 1.5;
  color: #495057;
  border: 1px solid transparent;
  border-radius: 0.25rem;
  transition: font-size 0.1s ease-in-out, top 0.1s ease-in-out;
}

label.floating-label input:-ms-input-placeholder {
  padding-top: 0;
  font-size: 1em;
}

label.floating-label input:-ms-input-placeholder + span {
  top: 0.3em;
  font-size: 1em;
}

label.floating-label input:placeholder-shown {
  padding-top: 0;
  font-size: 1em;
}

label.floating-label input:placeholder-shown + span {
  top: 0.3em;
  font-size: 1em;
}