.btn-file {

      display: inline-block;

      padding: 8px 12px;

      cursor: pointer;

      background: #89f;

      color: #345;

      position: relative;

      overflow: hidden;

    }

​

    .btn-file input[type=file] {

      position: absolute;

      top: 0;

      right: 0;

      min-width: 100%;

      min-height: 100%;

      filter: alpha(opacity=0);

      opacity: 0;

      cursor: inherit;

      display: block;

    }