/* Stili Generali e Responsive Design */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: #f4f7f6;
    color: #333;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
    box-sizing: border-box;
}

header {
    width: 100%;
    max-width: 600px;
    text-align: center;
    margin-bottom: 30px;
}

.import-section {
    background-color: #fff;
    padding: 15px;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

/* Stili Flashcard */
#flashcard-container {
    width: 100%;
    max-width: 600px;
    perspective: 1000px; /* Per animazioni 3D future */
}

#flashcard {
    background-color: #fff;
    border-radius: 12px;
    padding: 30px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
    text-align: center;
    min-height: 200px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

.question-text {
    font-size: 1.5em;
    margin-bottom: 20px;
    font-weight: 500;
}

/* Input e Controlli */
#user-input {
    width: 80%;
    padding: 12px;
    margin: 10px 0;
    border: 2px solid #ddd;
    border-radius: 8px;
    font-size: 1em;
    text-align: center;
}

#show-answer-btn {
    background-color: #007bff;
    color: white;
    padding: 12px 25px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.3s;
    margin-top: 10px;
}

#show-answer-btn:hover:not(:disabled) {
    background-color: #0056b3;
}

#show-answer-btn:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}

/* Retro Card Stili */
.card-face.hidden {
    display: none;
}

.label {
    font-weight: bold;
    color: #555;
    margin-top: 15px;
    font-size: 0.9em;
}

.solution-text {
    font-size: 1.6em;
    color: #28a745;
    font-weight: bold;
    margin: 5px 0;
}

.context-text {
    font-style: italic;
    color: #6c757d;
    margin-bottom: 25px;
}

/* Controlli SRS (Ripetizione Dilazionata) */
.srs-controls {
    display: flex;
    justify-content: space-around;
    margin-top: 20px;
}

.srs-btn {
    padding: 10px 15px;
    border: none;
    border-radius: 8px;
    color: white;
    cursor: pointer;
    font-weight: bold;
    transition: opacity 0.3s;
}

.srs-btn:hover {
    opacity: 0.9;
}

.hard { background-color: #dc3545; } /* Rosso per Difficile */
.medium { background-color: #ffc107; color: #333; } /* Giallo per Normale */
.easy { background-color: #28a745; } /* Verde per Facile */

#message-area {
    margin-top: 20px;
    color: #dc3545;
}