body {
  font-family: "Roboto", sans-serif;
  background-color: rgb(30, 30, 30);
}

.main-container {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;

  /* You need to define an explicit height! */
  height: 100vh;
}

h1 {
  color: rgb(200, 200, 200);
  font-size: 3em;
}