* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.pic-parent {
  width: 498px;
  height: 410px;
  position: relative;
  overflow: hidden;
  border-radius: 3px;
  box-shadow: 0 0 1px #999, -2px 2px 3px rgba(0, 0, 0, 0.2);
  background-image: url(1.png);
  background-size: cover;
}

.pic-child {
  position: absolute;
  height: 410px;
  top: 0;
  left: 0;
  min-width: 0;
  max-width: 498px;
  background-image: url(2.png);
  background-size: cover;
}

.pic-child::before {
  content: "↔";
  position: absolute;
  background-color: rgba(0, 0, 0, 0.5);
  font-size: 16px;
  color: white;
  top: 0;
  right: 0;
  line-height: 410px;
}

.resize-element {
  position: relative;
  top: 50%;
  left: 0;
  height: 15px;
  max-width: 498px;
  min-width: 15px;
  width: 0;
  opacity: 0;
  resize: horizontal;
  overflow: scroll;
  cursor: move;
  transform: scaleY(35);
  transform-origin: center center;
}