#tinymce span.shortcode-highlighter-container {
    -webkit-border-radius: 6px;
    -moz-border-radius: 6px;
    border-radius: 6px;
    padding: 1px;
    border-width:1px;
    border-style:solid;    
    font-size:15px;
    font-family: 'Courier New'
}