.timeline li {
  border-left: 3px solid #ddd;
  padding-left: 12px;
  position: relative;
}
.timeline li::before {
  content: "";
  width: 10px;
  height: 10px;
  background: #999;
  border-radius: 50%;
  position: absolute;
  left: -6px;
  top: 6px;
}