.flashcard-app {
    max-width: 600px;
    margin: 0 auto;
}

.start-screen {
    text-align: center;
    padding: 2rem;
}

.start-btn {
    background: var(--primary);
    color: white;
    border: none;
    padding: 0.8rem 2rem;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    margin-top: 1rem;
    transition: background 0.3s;
}

.start-btn:hover {
    background: var(--secondary);
}

.start-btn.disabled {
    background: var(--gray);
    cursor: not-allowed;
}

.empty-message {
    color: var(--danger);
    margin-top: 1rem;
}

.study-mode {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.deck-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.reset-btn {
    background: var(--warning);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    cursor: pointer;
}

.flashcard {
    background: var(--color-success-b);
    border-radius: 12px;
    color: var(--color-success);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    min-height: 60vh;
    display: flex
;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    text-align: center;
    font-size: 1.2rem;
    cursor: pointer;
    user-select: none;
    touch-action: pan-y;
    transition: transform 0.2s;
}

.flashcard:active {
    transform: scale(0.98);
        background: var(--color-success);

}

.front, .back {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.controls {
    display: flex;
    gap: 1rem;
    justify-content: space-between;
}

.nav-btn, .flip-btn {
    flex: 1;
    padding: 0.8rem;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
}

.nav-btn {
    background: var(--light);
    color: var(--dark);
}

.nav-btn.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.flip-btn {
    background: var(--primary);
    color: white;
}

@media (max-width: 480px) {
    .controls {
        flex-direction: row;
    }
    
    .flashcard {
        padding: 1.5rem;
        font-size: 1rem;
    }
    
    .nav-btn, .flip-btn {
        padding: 0.7rem;
        font-size: 0.8rem;
    }
}