.container{position:fixed;inset:0;display:flex;overflow:hidden}.leftPane{width:20%;background:#f9f9f9;border-right:1px solid #ddd;overflow-y:auto}.rightPane{width:80%;padding:16px;overflow-y:auto}.list{list-style:none;padding:0;margin:0}.listItem{padding:12px;cursor:pointer;border-bottom:1px solid #eee}.listItem.selected{color:orange;font-weight:600}