$green: #00ff00;

body {
  font-family: sans-serif;
  font-size: 16px;
}

.structure {
  margin-left: auto;
  margin-right: auto;
  width: 600px;
}

h1 {
    color: $green;
}

.deep {
  border-left: 2px solid black;
  padding: 1em;
}