<!DOCTYPE html>
<style>
.box {
  width: 100px;
  height: 10000px;
}
.container {
  width: 50px;
  height: 50px;
  background-color: rgb(100, 100, 0);
}
</style>
<body>
  <div class='box'></div>
  <div class='container'></div>
</body>