body {
    margin: 0;
    font-family: 'Segoe UI', sans-serif;
    background: #fdfdfd;
    color: #333;
  }
  
  header {
    text-align: center;
    background: #00796b;
    color: white;
    padding: 30px 10px;
  }
  
  header h1 {
    font-size: 2em;
    margin: 0;
  }
  
  .subtitle {
    font-size: 1rem;
    margin-top: 10px;
  }
  
  .card-container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 400px;
    padding: 20px;
    position: relative;
    overflow: hidden;
  }
  
  .flashcard {
    position: absolute;
    width: 90%;
    max-width: 400px;
    padding: 20px;
    background: #fff;
    border-radius: 15px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
    opacity: 0;
    transform: scale(0.95);
    transition: opacity 1s ease, transform 1s ease;
    pointer-events: none;
  }
  
  .flashcard.active {
    opacity: 1;
    transform: scale(1);
    pointer-events: auto;
  }
  
  .flashcard h2 {
    color: #00796b;
    margin-top: 0;
  }
  
  .flashcard ul {
    list-style: none;
    padding: 0;
  }
  
  .flashcard ul li {
    margin: 8px 0;
  }
  
  button {
    margin-top: 15px;
    padding: 10px 15px;
    background-color: #00796b;
    color: white;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 1rem;
  }
  
  button:hover {
    background-color: #00695c;
  }
  
  .signup-form {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 10px;
  }
  
  .signup-form input,
  .signup-form select {
    padding: 10px;
    border-radius: 8px;
    border: 1px solid #ccc;
    font-size: 1rem;
  }
  
  .thank-you-message {
    color: green;
    margin-top: 15px;
    font-weight: bold;
  }
  
  footer {
    background: #eeeeee;
    text-align: center;
    padding: 15px;
    font-size: 0.9rem;
    color: #555;
  }