It’ll take a little more than that, but it’s do-able:
add_filter( 'generate_start_widget_title','tu_add_span_widget_title' );
function tu_add_span_widget_title()
{
return '<div class="widget-title"><span>';
}
add_filter( 'generate_end_widget_title','tu_add_span_widget_title_end' );
function tu_add_span_widget_title_end()
{
return '</span></div>';
}
Adding PHP: https://generatepress.com/knowledgebase/adding-php-functions/
.sidebar .widget .widget-title {
border-bottom: 2px solid #000;
}
.sidebar .widget .widget-title span {
background: #000;
color: #FFF;
padding: 0 5px;
display: inline-block;
}
Adding CSS: https://generatepress.com/knowledgebase/adding-css/
Hope this helps ๐