body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
    background: #f4f4f4;
    min-height: 100vh;
  }
  
  .quiz-container {
    width: 100%;
    max-width: 500px;
    background: white;
    padding: 20px;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    margin: auto;
  }
  
  header {
    text-align: center;
    margin-bottom: 20px;
  }
  
  #question {
    font-size: 1.2rem;
    margin-bottom: 15px;
  }
  
  .options-container {
    display: grid;
    gap: 10px;
    margin-bottom: 20px;
  }
  
  .option {
    padding: 10px;
    background: #eee;
    border: none;
    border-radius: 3px;
    cursor: pointer;
  }
  
  .option:hover {
    background: #ddd;
  }
  
  .option.correct { background: #a1e6a1; }
  .option.incorrect { background: #ffb3b3; }
  
  .controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  
  #next-btn {
    padding: 8px 15px;
    background: #4CAF50;
    color: white;
    border: none;
    border-radius: 3px;
    cursor: pointer;
  }
  
  #next-btn:disabled {
    background: #ccc;
    cursor: not-allowed;
  }
  
  .results-container, .hidden { 
    text-align: center;
    padding: 20px 0; 
  }
  .hidden { display: none; }
  
  #progress {
    font-weight: bold;
    color: #555;
    margin: 10px 0;
  }
  
  @media (min-width: 900px) {
    .quiz-container { max-width: 900px; }
    .question-container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 30px;
      padding: 10px;
    }
    #question { align-self: center; }
  }