body {
    font-family: Arial, sans-serif;
    text-align: center;
    background: #f2f2f2;
    margin: 0;
    padding: 0;
  }
  
  #subject-selection,
  #flashcard-container {
    margin-top: 50px;
  }
  
  ul {
    list-style: none;
    padding: 0;
  }
  
  li {
    margin: 10px 0;
  }
  
  /* 과목 링크 스타일 */
  a {
    text-decoration: none;
    color: #007bff;
    font-size: 18px;
  }
  
  a:hover {
    text-decoration: underline;
  }
  
  button {
    margin: 5px;
    padding: 10px 15px;
    font-size: 16px;
    cursor: pointer;
  }
  
  /* 플래시카드 스타일 */
  #flashcard {
    background: #fff;
    border: 2px solid #ccc;
    border-radius: 8px;
    width: 300px;
    height: 500px;
    margin: 20px auto;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
  }
  
  /* 화면 숨김 */
  .hidden {
    display: none;
  }