body {
    font-family: Arial, sans-serif;
    background-color: #f9f9f9;
    color: #333;
    line-height: 1.6;
    margin: 20px;
  }
  
  /* Titles */
  h1, h2, h3 {
    color: #2c3e50;
  }
  
  h1 {
    font-size: 28px;
    margin-bottom: 20px;
  }
  
  h2 {
    font-size: 22px;
    margin-top: 30px;
  }
  
  /* Paragraphs */
  p {
    margin-bottom: 15px;
  }
  
  /* Links */
  a {
    color: #3498db;
    text-decoration: none;
  }
  
  a:hover {
    text-decoration: underline;
  }
  
  /* Code blocks or formulas */
  .formula, pre {
    background-color: #f2f2f2;
    padding: 10px;
    border-left: 4px solid #3498db;
    font-family: monospace;
    overflow-x: auto;
  }
  
  /* Lists */
  ul, ol {
    padding-left: 20px;
    margin-bottom: 15px;
  }
  
  /* Footer */
  footer {
    margin-top: 40px;
    font-size: 14px;
    text-align: center;
    color: #777;
  }
  .main-footer ul li {
    display: inline-block;
    margin: 0 10px;
  }
  
  .main-footer ul li a {
    color: #aaa;
    text-decoration: none;
  }
  
  .main-footer ul li a:hover {
    text-decoration: underline;
  }