If you want to change the style of both columns under Break By category, you can try to use the script below and adjust it to your needs:
widget.on("ready", function(w, args) {
var style = {
'font-size' : '12px'
,'font-weight' : 'bold'
,'color' : 'white'
,'background-color' : '#7a7a7a'
,'text-align' : 'center'
,'vertical-align' : 'middle'
}
//header columns
$(".p-dim-member-head", element).css(style);
$(".p-measure-head", element).css(style);
});The result is below:
