---

body {
  color: white;
  background: #FF66f0;
}

h1 {
  color: #0000ff;
  padding: 5px;
}

h2 {
  background: #E6E6FF;
  color: #ff0000;
  padding: 5px;
}

.formula {
  text-align: center;
  font-style: italic;
  font-weight: bold;
  color: #0000ff;
}

p.definition {
  border: 3px solid green;
  padding: 10px;
}