Try This
input[type=text] {
background: transparent;
border: none;
border-bottom: 1px solid #000000;
}
you can set padding though
padding: 5px 5px;
change it as per your page
or may even this can do that
border: 1px solid black;
float: left;
margin: 0;
padding: 0;
border-top: 0px;
border-left: 0px;
border-right: 0px;