default.css

html,
body {
  padding: 0;
  margin: 0;
  font-family: arial, helvetica;
  font-size: 16px;
}

.nav {
  z-index: 100;
  padding: 20px;
  font-size: 20px;
  position: fixed;
  box-sizing: border-box;
  left: 0;
  top: 0;
  bottom: 0;
  background-color: rgba(255, 255, 255, .2);
  display: flex;
  flex-direction: column;
  width: 20px;
  align-items: center;
  justify-content: center;
}

.nav a {
  text-align: center;
  display: block;
  cursor: pointer;
}

.wrapper {
  width: 100%;
  height: 100vh;
  overflow: hidden;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
}

.container {
  transition: linear 0.6s transform;
}

section {
  height: 100vh;
  box-sizing: border-box;
  padding: 40px 80px;
}

section:nth-of-type(even) {
  background-color: rgba(0, 0, 0, .1);
}

section:nth-of-type(odd) {
  background-color: rgba(0, 0, 0, .3);
}