section {
  padding-bottom: 100px;
  width: 772px;
  margin: 0 auto;
}

h1 {
  text-align: center;
  margin: 40px auto 30px;
  font-size:2em;
}
section p {
  text-align: right;
  color:red;
  font-style: italic;
  font-size:14px;
  font-weight: bold;
}

.demo_img {
  position:relative;
  margin:10px auto 5px;
  display: block;
  border:2px solid black;

  max-width:768px;
  max-height:512px;
}

ul {
  max-width:768px;
  margin:20px auto 50px;
}

li {
  list-style: initial;
  margin:0 0 5px 20px;
}
.demo_img:hover {
  cursor:col-resize;
}

.demo_img:before {
  content:"";
  padding-top:60%;
  display:block;
}

.demo_img > div {
  position:absolute;
  left:0;
  width:100%;
  top:0;
  height:100%;
  background-size:768px auto;
}

.demo_img > .pic2 {
  width:50%;
  border-right: 3px solid white;
}

#exterior, #interior  {
  width:100%;
}

#exterior .pic1 {
  background-image: url(for_realtors/exterior-house-before.jpg);
}

#exterior .pic2 {
  background-image: url(for_realtors/exterior-house-after.jpg);
}

#interior .pic1 {
  background-image: url(for_realtors/interior-room-before.jpg);
}

#interior .pic2 {
  background-image: url(for_realtors/interior-room-after.jpg);
}