Style

body {
  font-size: 20px;
}

#titulo {
  text-align: center;
}

input {
  width: 100%;
  margin-bottom: 10px;
  padding: 10px;
  box-sizing: border-box;
  border-radius: 5px;
  border: 1px solid;
}

input[type="submit"] {
  background-color: green;
  color: white;
}