.btn-back:hover {
    color: #f8fafc;
    background: rgba(255, 255, 255, 0.1);
}

.decks-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 1rem;
    margin-top: 1.5rem;
    transition: all 0.3s ease; /* Smooth toggle */
}

.decks-grid.collapsed {
    display: none !important;
}

/* Collapsible Sub-decks Header */
.subdecks-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: 2rem;
    margin-bottom: 0.5rem;
    cursor: pointer;
    user-select: none;
    transition: opacity 0.2s ease;
}

.subdecks-header:hover {
    opacity: 0.8;
}

.subdecks-header h3 {
    white-space: nowrap;
}

.subdecks-header .toggle-icon {
    font-size: 0.8rem;
    color: #3b82f6;
    transition: transform 0.2s ease;
}

.subdecks-line {
    flex-grow: 1;
    height: 1px;
    background: linear-gradient(90deg, rgba(255, 255, 255, 0.1) 0%, transparent 100%);
}

.deck-card {
    background: var(--bg-card, #1f1f1f);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 16px;
    padding: 1.5rem;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    backdrop-filter: blur(10px);
}

.deck-card:hover {
    transform: translateY(-5px);
    border-color: rgba(59, 130, 246, 0.5);
    box-shadow: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
}

.deck-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    background: rgba(255, 255, 255, 0.05);
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
}

.deck-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: #f8fafc;
    margin-bottom: 0.5rem;
}

.deck-meta {
    font-size: 0.85rem;
    color: #94a3b8;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.deck-progress {
    margin-top: auto;
}

.progress-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.8rem;
    color: #cbd5e1;
    margin-bottom: 0.5rem;
}

.progress-bar-bg {
    height: 6px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
    overflow: hidden;
}

.progress-bar-fill {
    height: 100%;
    background: #3b82f6;
    border-radius: 3px;
    transition: width 0.5s ease;
}

/* Dual-layout deck cards: desktop vs mobile */
.deck-card-desktop {
    display: block;
}

.deck-card-mobile {
    display: none;
}

@media (max-width: 768px) {
    .deck-card-desktop {
        display: none;
    }

    .deck-card-mobile {
        display: flex;
        align-items: center;
        gap: 0.6rem;
    }

    .decks-grid {
        grid-template-columns: 1fr !important;
    }

    .deck-card {
        max-width: none !important;
        padding: 0.7rem 0.8rem !important;
    }

    .add-deck-card {
        min-height: auto !important;
    }
}

/* Badge for System/User Decks */
.deck-badge {
    position: static;
    padding: 4px 8px;
    border-radius: 6px;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
}

/* Action buttons (edit/delete) */
.deck-action-btn {
    background: rgba(255, 255, 255, 0.06);
    border: none;
    color: #64748b;
    cursor: pointer;
    font-size: 0.65rem;
    padding: 4px 6px;
    border-radius: 5px;
    transition: all 0.2s ease;
}

.deck-action-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    color: #93c5fd;
    transform: scale(1.15);
}

.deck-action-btn--delete:hover {
    color: #f87171;
    background: rgba(248, 113, 113, 0.12);
}

.badge-system {
    background: rgba(16, 185, 129, 0.2);
    color: #34d399;
}

.badge-user {
    background: rgba(59, 130, 246, 0.2);
    color: #60a5fa;
}

/* Add Deck Button */
.add-deck-card {
    border: 2px dashed rgba(255, 255, 255, 0.1);
    background: transparent;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    min-height: 200px;
}

.add-deck-card:hover {
    border-color: #3b82f6;
    background: rgba(59, 130, 246, 0.05);
}

.add-content {
    text-align: center;
    color: #94a3b8;
}

/* Breadcrumbs */
.breadcrumbs {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 2rem;
    margin-bottom: 1rem;
    font-size: 1.1rem;
    color: #94a3b8;
}

.crumb-link {
    cursor: pointer;
    color: #60a5fa;
    transition: color 0.2s;
}

.crumb-link:hover {
    color: #93c5fd;
}

.crumb-active {
    color: #f8fafc;
    font-weight: 600;
}

.crumb-separator {
    font-size: 0.8rem;
    color: #475569;
}

/* --- SRS Status Indicators for Card Rows --- */
.card-row-item {
    border-left: 6px solid transparent; /* Increased from 4px */
    transition: all 0.25s ease;
    border-radius: 8px; /* Added rounded corners for a more modern look */
}

.srs-status-forgot {
    border-left-color: #f87171; /* Brighter Red */
    background: linear-gradient(90deg, rgba(248, 113, 113, 0.1) 0%, transparent 100%);
}

.srs-status-hard {
    border-left-color: #fb923c; /* Brighter Orange */
    background: linear-gradient(90deg, rgba(251, 146, 60, 0.1) 0%, transparent 100%);
}

.srs-status-good {
    border-left-color: #60a5fa; /* Brighter Blue */
    background: linear-gradient(90deg, rgba(96, 165, 250, 0.1) 0%, transparent 100%);
}

.srs-status-easy {
    border-left-color: #34d399; /* Brighter Green */
    background: linear-gradient(90deg, rgba(52, 211, 153, 0.1) 0%, transparent 100%);
}

/* --- Efecto Pendiente (Due) --- */
.is-due-glow {
    animation: duePulseGlow 2.5s infinite;
    border: 1px solid rgba(59, 130, 246, 0.3);
}

@keyframes duePulseGlow {
    0% {
        box-shadow: 0 0 0 0 rgba(59, 130, 246, 0.4);
    }

    70% {
        box-shadow: 0 0 0 8px rgba(59, 130, 246, 0);
    }

    100% {
        box-shadow: 0 0 0 0 rgba(59, 130, 246, 0);
    }
}

/* --- Optimized UI Components (Added during Refactor) --- */
.action-bar {
    display: flex;
    gap: 0.8rem;
    align-items: center;
    flex-wrap: wrap;
}

.btn-premium {
    height: 42px;
    padding: 0 1.5rem;
    border-radius: 12px;
    font-weight: 600;
    font-size: 0.95rem;
    border: none;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.6rem;
    cursor: pointer;
    box-sizing: border-box;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.btn-premium-primary {
    background: #3b82f6;
    color: white;
    box-shadow: 0 4px 6px -1px rgba(59, 130, 246, 0.3);
}

.btn-premium-primary:hover {
    transform: translateY(-2px);
    background: #2563eb;
}

.btn-premium-secondary {
    background: rgba(30, 41, 59, 0.6);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: #e2e8f0;
}

.btn-premium-secondary:hover {
    background: rgba(51, 65, 85, 0.8);
}

.btn-premium-ia {
    background: rgba(139, 92, 246, 0.15);
    border: 1px solid rgba(139, 92, 246, 0.3);
    color: #d8b4fe;
}

.btn-premium-ia:hover {
    background: rgba(139, 92, 246, 0.25);
}

.card-row-item {
    display: grid;
    grid-template-columns: 45px 1fr 1fr 80px;
    gap: 1rem;
    padding: 1rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    align-items: center;
    transition: all 0.2s;
    cursor: grab;
    border-radius: 8px;
    margin-bottom: 4px;
    border-left: 4px solid transparent;
    user-select: none;
}

.card-row-item:hover {
    filter: brightness(1.3);
    background: rgba(255, 255, 255, 0.02);
}

.card-row-front {
    color: #cbd5e1;
    font-weight: 500;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.card-row-back {
    color: #94a3b8;
    font-size: 0.95rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.card-row-actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
}

.deck-icon-large {
    width: 60px;
    height: 60px;
    font-size: 2rem;
    background: rgba(59, 130, 246, 0.1);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid rgba(59, 130, 246, 0.2);
    flex-shrink: 0;
}

.card-checkbox {
    accent-color: #3b82f6;
    width: 16px;
    height: 16px;
    cursor: pointer;
}

.drag-handle {
    cursor: grab;
    font-size: 1rem;
    padding: 10px;
    color: #64748b;
}

@media (max-width: 640px) {
    .card-row-item {
        grid-template-columns: 40px 1fr 80px;
    }
    .card-row-back {
        display: none;
    }
}