html, body{
  margin: 0;
  padding: 0;
  font-family: 'Courier New', Courier, monospace;
}

h1 {
  font-size: 3em;
}

#article {
  font-size: 2em;
  margin: 50px;
}

#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  color: #2c3e50;
  margin-top: 60px;
}

#left, #demo{
  padding: 0 30px;
  float: left;
  max-width: 700px;
}

#code {
  font-family: source-code-pro, Menlo, Monaco, Consolas, "Courier New", monospace;
  overflow: auto;
  white-space: pre-wrap;
}