body {
  font-family: sans-serif;
  text-align: center;
  margin: 0;
  padding: 0;
  background-color: #f9f9f9;
}

h1 {
  margin-top: 20px;
}

#buttons {
  margin: 20px;
}

button {
  padding: 10px 20px;
  margin: 5px;
  font-size: 16px;
  cursor: pointer;
}

#chart {
  margin: auto;
  width: 90%;
  max-width: 1000px;
}