body {
  font-family: 'Georgia', 'Times New Roman', serif;
  background: #fefefe;
  padding: 2rem;
  max-width: 800px;
  margin: auto;
  line-height: 1.7;
  color: #111;
}

h1 {
  text-align: center;
  font-size: 2rem;
  font-weight: normal;
  border-bottom: 1px solid #ccc;
  padding-bottom: 0.5rem;
  margin-bottom: 2rem;
}

.formula {
  margin-bottom: 2.5rem;
  padding: 1rem 1rem 1.5rem 1rem;
  border-bottom: 1px dotted #ccc;
}

.formula-title {
  font-weight: bold;
  font-size: 1.2rem;
  margin-bottom: 0.5rem;
}

.formula-expression {
  text-align: center;
  font-size: 1.3rem;
  margin: 1rem 0;
}

.formula-description {
  font-style: italic;
  font-size: 0.95rem;
  color: #444;
  text-align: justify;
}