Css Layouts 101 - Getting Confused In Structuring Layout

For this layout, the easiest structuring method I can find with pure css is by using the vh unit. Since its a bit restrictive in its support and the requirement being to go with on

Solution 1:

Check if this is what you are looking for:

* {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
  padding: 0;
  font-size: 22px;
  text-transform: uppercase;
}
body {
  padding-top: 100vh;
}
.cover {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  background: #eee;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}
footer {
  background: #222;
  color: #fff;
  display: flex;
  height: 60px;
  align-items: center;
  justify-content: center;
  z-index: 999;
}
section {
  padding: 10px;
  margin: 25px;
  border: 1px solid #000;
}

<divclass="cover">cover</div><section>
  section 1
  <br/>section 1
  <br/>section 1
  <br/>section 1
  <br/>section 1
  <br/>section 1
  <br/>section 1
  <br/></section><section>
  section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/>section 2
  <br/></section><section>
  section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/>section 3
  <br/></section><footer>footer</footer>