javascript - How to Add "custom Class name" to bing Map Infobox -

i creating infoboxes on map, , want change/add default class name. way creating infoboxes.

infoboxoptions = new microsoft.maps.infobox(point,{                    class:'new-class-name'                    title: 'title',                    description: address,                    visible: true,                    offset: new microsoft.maps.point(0, 15),                    showclosebutton: false,                }); 

so can add "class:'new-class-name'" class name infobox

to need create custom html includes class name , pass htmlcontent property of infobox. can find example on how create custom infobox using html here: https://msdn.microsoft.com/en-us/library/mt750271.aspx