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

body {
  font-family: sans-serif;
  background: red;
}

.header {
  position: sticky;
  top: 0;
  color: white;
  background: blue;
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 3px solid white;
  z-index: 2;
}

.title {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: yellow;
  border: 3px solid black;
}

section {
  margin: 16px;
  background: green;
  height: 1000px;
}

.content {
  position: sticky;
  top: 121px;
  border: 3px solid white;
  z-index: 1;
}

.spacer {
  height: 500px;
}