.before_after_slider {
  position: relative;
  width: 640px;
  height: 480px;
  margin:0 auto;
}

.before_after_slider > * {
  position: absolute;
}

.after {
  overflow: hidden;
}

.separator_line {
	height: 100%;
	border: 1px solid #fafafa;
    position: absolute;
}