sovrapposizione testo su campo input

[dropper]

Buongiorno stavo creando un form di inserimento dati in stile material, ma ho un problema legato alla sovrapposizione del nome dell'etichetta al contenuto che vado ad inserire nel form.
La transizione focus funziona alla perfezione ma quando clicco su un altra etichetta avviene il problema.

metto il codice:

             <div class="input-field">
                    <input id="first_name"  type="text" class="validate">          
                    <label for="first_name" >Nome</label>        
            </div>

input[type=text], input[type=password], input[type=email], input[type=url], input[type=time], input[type=date], input[type=datetime-local], input[type=tel], input[type=number], input[type=search], textarea.materialize-textarea {
  background-color: transparent;
  border: none;
  border-bottom: 1px solid #9e9e9e;
  border-radius: 0;
  outline: none;
  height: 3rem;
  width: 100%;
  font-size: 1rem;
  margin: 0 0 15px 0;
  padding: 0;
  box-shadow: none;
  -webkit-box-sizing: content-box;
  -moz-box-sizing: content-box;
  box-sizing: content-box;
  transition: all .3s; }

  input[type=text]:disabled, input[type=text][readonly="readonly"], input[type=password]:disabled, input[type=password][readonly="readonly"], input[type=email]:disabled, input[type=email][readonly="readonly"], input[type=url]:disabled, input[type=url][readonly="readonly"], input[type=time]:disabled, input[type=time][readonly="readonly"], input[type=date]:disabled, input[type=date][readonly="readonly"], input[type=datetime-local]:disabled, input[type=datetime-local][readonly="readonly"], input[type=tel]:disabled, input[type=tel][readonly="readonly"], input[type=number]:disabled, input[type=number][readonly="readonly"], input[type=search]:disabled, input[type=search][readonly="readonly"], textarea.materialize-textarea:disabled, textarea.materialize-textarea[readonly="readonly"] {
    color: rgba(0, 0, 0, 0.26);
    border-bottom: 1px dotted rgba(0, 0, 0, 0.26); }

  input[type=text]:disabled + label, input[type=text][readonly="readonly"] + label, input[type=password]:disabled + label, input[type=password][readonly="readonly"] + label, input[type=email]:disabled + label, input[type=email][readonly="readonly"] + label, input[type=url]:disabled + label, input[type=url][readonly="readonly"] + label, input[type=time]:disabled + label, input[type=time][readonly="readonly"] + label, input[type=date]:disabled + label, input[type=date][readonly="readonly"] + label, input[type=datetime-local]:disabled + label, input[type=datetime-local][readonly="readonly"] + label, input[type=tel]:disabled + label, input[type=tel][readonly="readonly"] + label, input[type=number]:disabled + label, input[type=number][readonly="readonly"] + label, input[type=search]:disabled + label, input[type=search][readonly="readonly"] + label, textarea.materialize-textarea:disabled + label, textarea.materialize-textarea[readonly="readonly"] + label {
    color: rgba(0, 0, 0, 0.26); }

  input[type=text]:focus:not([readonly]), input[type=password]:focus:not([readonly]), input[type=email]:focus:not([readonly]), input[type=url]:focus:not([readonly]), input[type=time]:focus:not([readonly]), input[type=date]:focus:not([readonly]), input[type=datetime-local]:focus:not([readonly]), input[type=tel]:focus:not([readonly]), input[type=number]:focus:not([readonly]), input[type=search]:focus:not([readonly]), textarea.materialize-textarea:focus:not([readonly]) {
    border-bottom: 1px solid #26a69a;
    box-shadow: 0 1px 0 0 #26a69a; }

  input[type=text]:focus:not([readonly]) + label, input[type=password]:focus:not([readonly]) + label, input[type=email]:focus:not([readonly]) + label, input[type=url]:focus:not([readonly]) + label, input[type=time]:focus:not([readonly]) + label, input[type=date]:focus:not([readonly]) + label, input[type=datetime-local]:focus:not([readonly]) + label, input[type=tel]:focus:not([readonly]) + label, input[type=number]:focus:not([readonly]) + label, input[type=search]:focus:not([readonly]) + label, textarea.materialize-textarea:focus:not([readonly]) + label {
    color: #26a69a;
    font-size: 0.8rem;
    -webkit-transform: translateY(-140%);
    -moz-transform: translateY(-140%);
    -ms-transform: translateY(-140%);
    -o-transform: translateY(-140%);
    transform: translateY(-140%);  }

  input[type=text].valid, input[type=text]:focus.valid, input[type=password].valid, input[type=password]:focus.valid, input[type=email].valid, input[type=email]:focus.valid, input[type=url].valid, input[type=url]:focus.valid, input[type=time].valid, input[type=time]:focus.valid, input[type=date].valid, input[type=date]:focus.valid, input[type=datetime-local].valid, input[type=datetime-local]:focus.valid, input[type=tel].valid, input[type=tel]:focus.valid, input[type=number].valid, input[type=number]:focus.valid, input[type=search].valid, input[type=search]:focus.valid, textarea.materialize-textarea.valid, textarea.materialize-textarea:focus.valid {
    border-bottom: 1px solid #4CAF50;
    box-shadow: 0 1px 0 0 #4CAF50;
     }
    
  input[type=text].invalid, input[type=text]:focus.invalid, input[type=password].invalid, input[type=password]:focus.invalid, input[type=email].invalid, input[type=email]:focus.invalid, input[type=url].invalid, input[type=url]:focus.invalid, input[type=time].invalid, input[type=time]:focus.invalid, input[type=date].invalid, input[type=date]:focus.invalid, input[type=datetime-local].invalid, input[type=datetime-local]:focus.invalid, input[type=tel].invalid, input[type=tel]:focus.invalid, input[type=number].invalid, input[type=number]:focus.invalid, input[type=search].invalid, input[type=search]:focus.invalid, textarea.materialize-textarea.invalid, textarea.materialize-textarea:focus.invalid {
    border-bottom: 1px solid #F44336;
    box-shadow: 0 1px 0 0 #F44336; }

.input-field {
  position: relative;
  margin-top: 1rem; }
  .input-field label {
    color: #9e9e9e;
    position: absolute;
    top: 0.8rem;
    left: 0.75rem;
    font-size: 1rem;
    cursor: text;
    -webkit-transition: .2s ease-out;
    -moz-transition: .2s ease-out;
    -o-transition: .2s ease-out;
    -ms-transition: .2s ease-out;
    transition: .2s ease-out; }

  .input-field label.active {
    font-size: 0.8rem;
    -webkit-transform: translateY(-140%);
    -moz-transform: translateY(-140%);
    -ms-transform: translateY(-140%);
    -o-transform: translateY(-140%);
    transform: translateY(-140%); }

  .input-field .prefix {
    position: absolute;
    width: 3rem;
    font-size: 2rem;
    -webkit-transition: color .2s;
    -moz-transition: color .2s;
    -o-transition: color .2s;
    -ms-transition: color .2s;
    transition: color .2s; }

    .input-field .prefix.active {
      color: #26a69a; }

  .input-field .prefix ~ input, .input-field .prefix ~ textarea {
    margin-left: 3rem;
    width: 92%;
    width: calc(100% - 3rem); }

  .input-field .prefix ~ textarea {
    padding-top: .8rem; }

  .input-field .prefix ~ label {
    margin-left: 3rem; }

questo nel dettaglio è quello che mi succede.
problema.jpg

idee e suggerimenti? grazie