*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    /* font-family: 'Segoe UI', sans-serif;  */
    background: #f7f9fc;
    color: #333;
  }
  
  .container {
    max-width: 960px;
    margin: auto;
    padding: 20px;
  }
  
  h1, h2 {
    text-align: center;
    color: #2c3e50;
  }
  h4{
    margin-top: 10px;
  }
  
  .definition {
    font-size: 18px;
    margin-bottom: 30px;
    /* text-align: center; */
  }
  
  .math {
    font-size: 20px;
    display: block;
    margin: 10px 0;
  }
  
  .example-section {
    margin-bottom: 50px;
    padding: 20px;
    background: #ffffff;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    text-align: center;
  }
  
  canvas {
    border: 1px solid #ccc;
    margin-top: 20px;
  }
  
  .btn {
    display: inline-block;
    margin: 20px auto 0;
    padding: 10px 20px;
    background-color: #3498db;
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    transition: background-color 0.3s;
  }
  
  .btn:hover {
    background-color: #2980b9;
  }
  
  @media (max-width: 600px) {
    canvas {
      width: 100%;
      height: auto;
    }
  
    .btn {
      font-size: 14px;
      padding: 8px 16px;
    }
  }