input field with fa icon

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">

<div class="tutuclass">
<input type="email" placeholder="Username" id="tutu" required />
<i class="fa fa-user"></i>
</div>

CSS

.tutuclass #tutu{
    border-radius: 3px;
    border: 1px silver solid;
    padding-left: 10px;
    font-weight: bolder;
    color: #bcbcbc;
    height: 40px;
    width: 350px;
}
.tutuclass .fa {
  margin: auto -30px;
  color: #fff;
}
input[type="email"] {

        background: #000;
        padding-right: 50px; 
    }