I have use viwerJs for show the images. when I going to access the Css in my project I wanted to use javascript for that. So my problem was when I going to do fowllowing process I couldn't access ::before element to set the margin
here is the code I can do in css but i want to do thi in JS.
    .viewer-toolbar > ul > li::before{
  margin: 10px 0px 0px 10px !important;
}
.viewer-play::before {
    background-position: -97px 3px !important;
 } 
here is my try
 viewImage(event) {
    let viewer = new Viewer(event.currentTarget, {
      navbar: false,
      viewed() {
        debugger
        viewer.zoomTo(2);
        viewer['image'].style['border'] = "1px solid white";
        
        for (let t = 0; t < viewer['toolbar'].childNodes[0].childNodes.length; t++){
          let li = viewer['toolbar'].childNodes[0].childNodes[t];
          if(li.className === 'viewer-play viewer-large'){
            li.style.width = '46px';
            li.style.height = '46px';
            li.before.style.margin = '10px 0px 0px 10px'; // this my try but it not work
          }else{
            li.style.width = '40px';
            li.style.height = '40px';
          }
          
        }
      }
    });
    viewer.show();
  }
 
    