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

body {
  width: 100%;
  height: 100vh;
  display: grid;
  place-items: center;
}

.container {
  width: 800px;
  height: 400px;
  border: 5px solid black;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

.image1 {
  background: url(image1.jpg) center no-repeat fixed;
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  background-size: cover;
}

.box1 {
  width: 50%;
  height: 100%;
  overflow: hidden;
  position: relative;
}

.box2 {
  width: 50%;
  height: 100%;
  overflow: hidden;
  position: relative;
}

.image2 {
  position: absolute;
  top: 0;
  right: 0;
  width: 100%;
  height: 100%;
  background: url(image2.jpg) center no-repeat fixed;
  background-size: cover;
}

.line-div {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  align-items: center;
  height: 100%;
}

.arrow {
  position: relative;
  color: white;
  width: 100px;
  height: 100px;
  background-color: rgba(0, 0, 0, 0.7);
  box-shadow: 0px 0px 20px rgba(0, 0, 0, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-size: 2rem;
  cursor: pointer;
  z-index: 999;
  margin: auto 0;
}

.line {
  width: 8px;
  height: 100%;
  background-color: red;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}