.slider {
  display: flex;
  overflow: hidden;
  -webkit-overflow-scrolling: touch;
  position: relative;
  margin-bottom: 50px;
}

.content {
  margin: 0 auto;
  margin-top: 150px;
}

.slider > div {
  flex-shrink: 0;
  width: 300px;
  height: 300px;
  color: white;
  background: grey;
  line-height: 300px;
  font-size: 26px;
  text-align: center;
  font-weight: bold;
  background-repeat: no-repeat;
  background-size: cover;
  position: relative;
}

.marker {
  position: absolute;
  width: 1px;
  height: 100%;
  background: red;
  top: 0px;
  left: 50%;
  margin-left: -0.5px;
}

html, body {
  margin: 0;
  padding: 0;
}