.word-buttons {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 1rem;
    margin-top: 1rem;
  }
  
  .word-button {
    padding: 0.75rem 1.5rem;
    font-size: 1.2rem;
    border: none;
    border-radius: 8px;
    background-color: #1B2A5B;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s ease;
  }
  
  .word-button:hover {
    background-color: #324074;
  }
  
  .prompt {
    font-size: 1.4rem;
    font-weight: bold;
    margin-bottom: 1rem;
  }
  
  .correct {
    font-size: 1.4rem;
    color: #28a745;
  }
  
  .wrong {
    font-size: 1.4rem;
    color: #dc3545;
  }
  
  .next-button {
    margin-top: 1rem;
    padding: 0.6rem 1.2rem;
    font-size: 1rem;
    background-color: #FFA500;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
  }
  .back-button {
    position: absolute;
    top: 25px;
    left: 25px;
    background-color: var(--primary-blue); 
    color: var(--text-light);
    padding: 10px 20px; 
    border: none;
    border-radius: 10px; 
    font-size: 1em; 
    font-weight: 600; 
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
    z-index: 10;
    box-shadow: 0 3px 6px var(--shadow-light);
}

.back-button:hover {
    background-color: #5c8ae6; 
    transform: translateY(-3px);
    box-shadow: 0 5px 10px var(--shadow-medium);
}

.back-button:active {
    transform: translateY(0);
    box-shadow: 0 1px 3px var(--shadow-light);
}

/* Mobile-specific adjustments for very small screens */
@media (max-width: 480px) {
    .math-controls button {
        font-size: 1em;
        padding: 12px 25px;
    }
    .back-button {
        padding: 6px 12px;
        font-size: 0.8em;
        top: 15px; 
        left: 15px; 
        border-radius: 8px;
    }
    #math-problem-text {
        font-size: clamp(2em, 6vw, 4em); 
    }
    #answer-input {
        font-size: 1.2em;
        padding: 12px 15px;
    }
    #feedback-message {
        font-size: 1.4em;
    }
    .container {
        padding: 40px 20px 20px 20px; 
    }
}