css to create an underline input box_html/css_WEB-ITnose

Similar to this effect

<input type="text" class="input" />

Simple version

    border: 0;    outline: 0;    background: transparent;    border-bottom: 2px solid black;    width: 20px;

Slightly more complicated and beautiful

    background-color: transparent;        border: none;        border-bottom: 2px solid #fff;        outline: none;        padding-bottom: 10px;        text-align: center;        width: 400px;        font-size: 300%;        color: #fff;        font-weight: 100;