body {
  max-width: 320px;
  margin: auto;
  padding: 30px 20px;
  font-family: sans-serif;
  font-size: 14px;
}

/* Titres */
h1 {
  text-align: center;
  font-size: 20px;
}

/* Formulaires */
.btn,
button,
[type="submit"] {
  display: block;
  width: 200px;
  margin: 10px auto auto;
  padding: 8px 16px;
  text-align: center;
  color: blue;
  border: 1px solid blue;
  border-radius: 4px;
}

label,
input {
  display: inline;
}

/* Apparence */
section:not(:last-of-type) {
  margin-bottom: 30px;
}