body {
    font-family: Georgia, 'Times New Roman', Times, serif;
    background-color: #f4f1ea; /* Old paper color */
    color: #2c3e50;
    margin: 0;
    padding: 0;
  }
  
  .header {
    background-color: #1a252f;
    color: #ecf0f1;
    text-align: center;
    padding: 30px 20px;
    border-bottom: 5px solid #c0392b;
  }
  
  .header h1 {
    margin: 0;
    font-size: 2.5em;
    letter-spacing: 1px;
  }
  
  .container {
    max-width: 900px;
    margin: 30px auto;
    padding: 0 20px;
  }
  
  .section {
    background: #ffffff;
    padding: 25px;
    margin-bottom: 30px;
    border-radius: 8px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.05);
    border-left: 5px solid #2980b9;
  }
  
  h2 {
    color: #2980b9;
    border-bottom: 1px solid #eee;
    padding-bottom: 10px;
    margin-top: 0;
  }
  
  code {
    background: #eee;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: monospace;
  }
  
  input[type="text"] {
    width: 100%;
    padding: 15px;
    font-size: 1.2em;
    font-family: 'Courier New', Courier, monospace;
    box-sizing: border-box;
    border: 2px solid #bdc3c7;
    border-radius: 5px;
    margin-bottom: 15px;
  }
  
  .keyboard {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
  }
  
  .keyboard button {
    padding: 10px 15px;
    font-size: 1.1em;
    background: #ecf0f1;
    border: 1px solid #bdc3c7;
    border-radius: 5px;
    cursor: pointer;
    font-family: monospace;
  }
  
  .keyboard button:hover {
    background: #d5d8dc;
  }
  
  .input-group {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 20px;
  }
  
  .input-group input[type="number"] {
    width: 80px;
    padding: 8px;
    font-size: 1em;
  }
  
  button.btn-primary, button.btn-secondary {
    padding: 12px 25px;
    font-size: 1.1em;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-family: Georgia, serif;
  }
  
  button.btn-primary { background-color: #27ae60; }
  button.btn-primary:hover { background-color: #2ecc71; }
  
  button.btn-secondary { background-color: #2980b9; }
  button.btn-secondary:hover { background-color: #3498db; }
  
  .result-box {
    background: #f9fbfd;
    border: 1px solid #d6eaf8;
    padding: 20px;
    border-radius: 5px;
    margin-top: 20px;
    font-size: 1.1em;
    line-height: 1.6;
  }
  
  .hidden {
    display: none;
  }
  
  canvas {
    width: 100% !important;
    max-height: 400px;
  }