Fixing the background while the other elements in the page are scrollable makes your site professional. The following scripts is a long page with different fixed images, which vary by scrolling. Many web elements are available at the page, which are scrollable.

HTML
<!-- this script got from www.devanswer.com -->
<main> <div class="fixed-bg bg-1"> <h1 class="main-text">DevAnswer</h1> <p class="sub-text">What Developers Need!</p> </div> <div class="fixed-bg bg-1-1"> <div class="text-box"> <h2>Title</h2> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <img style="-webkit-user-select: none;" src="http://devanswer.com/codes/files/fixed-8.jpg"> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> </div> </div> <div class="fixed-bg bg-2"> <h1>The capital is Tórshavn.</h1> </div> <div class="fixed-bg bg-2-1"> <div class="text-box"> <h2>Title</h2> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <img src="http://devanswer.com/codes/files/fixed-9.jpg"> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> </div> </div> <div class="fixed-bg bg-3"> <h1>The capital is Tórshavn.</h1> </div> <div class="fixed-bg bg-3-1"> <div class="text-box"> <h2>Title</h2> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <img src="http://devanswer.com/codes/files/fixed-10.jpg"> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> <p> He lives with his wife and their three grown-up children in a village called Trøllanes on the most northerly tip of the island. The village sits in a hollow, smoothly rounded by glacial ice. To get to the village you must drive through a narrow one-way tunnel with no lighting. Before it was built in the 1970s the village could only be accessed by boat. </p> </div> </div> <div class="fixed-bg bg-4"> <h1>The capital is Tórshavn.</h1> </div> <div class="fixed-bg"> <h2>Thank You</h2> <p> Empower the Convergence of Strategic Analytics </p> </div> </main><a style="font-size: 8pt; text-decoration: none" target="_blank" href="http://www.devanswer.com">Developer Code</a>

CSS
body,
html,
main
{
  height: 100%;
  margin: auto 0;
  font-family: 'Raleway','Microsoft JhengHei';
}

.fixed-bg {
  min-height: 100%;
  background-size: cover;
  -webkit-background-size: cover !important; 
  -moz-background-size: cover !important; 
  -o-background-size: cover; 
  background-attachment: fixed;
  background-repeat: no-repeat;
  background-position: center center;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: 0 20px;
  line-height: 1.5;    
}

h1 {
  text-align: center;
  font-size: 3.5em;
  color: rgba(255, 255, 255, 1);
  text-shadow: 1px 1px 10px #000, 5px 5px 20px #000, 1px 0px 20px #def;
  opacity: 0.95;
}
img {
  width: 100%;
  height: auto;
}
.main-text {
  font-size: 5.5em;
  line-height:0px;
}
.sub-text{
  color:#fff;
  line-height:0px;
  text-shadow: 1px 1px 10px #000, 5px 5px 20px #000, 1px 0px 20px #def;
}
.text-box {
  background: rgba(255, 255, 255, 0.95);
  padding: 20px;
  margin: 0;
  max-width: 500px;
}
.fixed-bg h2 {
  font-size: 4em;
}
.fixed-bg p {
  text-align: center;
  max-width: 500px;
  font-size: 1.2em;
  text-align: left;
}

.bg-1 {
  background-image: url("http://devanswer.com/codes/files/fixed-1.jpg");
}
.bg-1-1 {
  background-image: url("http://devanswer.com/codes/files/fixed-2.jpg");
}
.bg-2 {
  background-image: url("http://devanswer.com/codes/files/fixed-3.jpg");
}
.bg-2-1 {
  background-image: url("http://devanswer.com/codes/files/fixed-4.jpg");
}
.bg-3 {
  background-image: url("http://devanswer.com/codes/files/fixed-5.jpg");
}
.bg-3-1 {
  background-image: url("http://devanswer.com/codes/files/fixed-6.jpg");
}
.bg-4 {
  background-image: url("http://devanswer.com/codes/files/fixed-7.jpg");
}