Bootstrap 3 button with transparent background

button.css

/**
 * Tested on Bootstrap 3.3.2 
 * Usage: <button class="btn btn-transparent" type="button">Click me</button>
 */
.btn-transparent {
    background: transparent;
    color: #F2F2F2;
    -webkit-transition: background .2s ease-in-out, border .2s ease-in-out;
    -moz-transition: background .2s ease-in-out, border .2s ease-in-out;
    -o-transition: background .2s ease-in-out, border .2s ease-in-out;
    transition: background .2s ease-in-out, border .2s ease-in-out;
    border: 2px solid #4992B7;
}

    .btn-transparent:hover {
        color: white;
        background-color: rgba(255,255,255,0.2);
    }