Edit in JSFiddle

<form>
  <div>
    <input type="text" name="_email" value="">
    <label for="email">Email-Adresse</label>
  </div>
</form>
form {
  margin-top: 50px;
  font-family: sans-serif;
}
form div {
  background: #FFF;
  border: 1px solid rgba(0,0,0,.2);
  position: relative;
  padding: 10px;
}
form div input {
  background: none;
  border: none;
  display: block;
  position: relative;
  z-index: 2;
}
form div label {
  color: rgba(0,0,0,.3);
  padding: 10px;
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  z-index: 1;
  transition: top .3s;
}
form div input:focus + label {
  color: rgba(0,0,0,.7);
  top:-30px;
}