Style a file input to match the rest of the form

/* the real input sits invisibly on top of a styled button */
.file-field { position: relative; overflow: hidden; display: inline-block; }

.file-field input[type="file"] {
    position: absolute;
    top: 0; right: 0; margin: 0;
    opacity: 0; filter: alpha(opacity=0);  /* IE8 */
    font-size: 100px;  /* enlarges the click target to cover the button */
    cursor: pointer;
}