.btn-file {
     position: relative;
     overflow: hidden;
     font: inherit;
}

.btn-file input[type=file] {
     position: absolute;
     top: 0;
     right: 0;
     min-width: 100%;
     min-height: 100%;
     font: inherit;
     text-align: right;
     filter: alpha(opacity=0);
     opacity: 0;
     outline: none;
     background: white;
     cursor: inherit;
     display: block;
}

.btn-file .glyphicon {
     margin-right: 5px;
}