<div class="container">

<header>
 header
</header>

<section id = "section-1">
  content
</section>

<section id = "section-2">
  content 2
</section>
</div>



html {
  height: 100%;
}

body {
height: 100%;
width: 100%;
margin: 0;
padding: 0;
  border: 3px solid black;
}

.container {

}

header {
  height: 100px;
  background: red;
}

#section-1 {
  height: 980px;
}

#section-2 {
  height: 1080px;
  background: red;
}