/* Backlog Split View */
.backlog-split {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    height: calc(100vh - 180px);
}

.backlog-split-panel {
    display: flex;
    flex-direction: column;
    background: var(--color-gray-50);
    border-radius: var(--border-radius-lg);
    border: 1px solid var(--color-gray-200);
    overflow: hidden;
}

.backlog-split-board {
    border: 2px solid var(--color-primary);
    background: rgba(37, 99, 235, 0.02);
}

.backlog-panel-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--color-white);
    border-bottom: 1px solid var(--color-gray-200);
}

.backlog-panel-header-board {
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
    color: white;
    border-bottom: none;
}

.backlog-panel-header-board .badge {
    background: rgba(255,255,255,0.2);
    color: white;
}

.backlog-panel-icon {
    font-size: var(--font-size-lg);
}

.backlog-panel-hint {
    padding: var(--spacing-xs) var(--spacing-lg);
    font-size: var(--font-size-xs);
    color: var(--color-gray-400);
    background: var(--color-white);
    border-bottom: 1px solid var(--color-gray-100);
}

.backlog-panel-body {
    flex: 1;
    padding: var(--spacing-sm);
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    min-height: 200px;
    transition: background var(--transition-fast);
}

.backlog-panel-body.drag-over {
    background: rgba(37, 99, 235, 0.08);
    border: 2px dashed var(--color-primary);
    border-radius: var(--border-radius-md);
}

.backlog-empty {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--color-gray-400);
}

/* Backlog Card */
.backlog-card {
    display: flex;
    align-items: stretch;
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--border-radius-md);
    cursor: grab;
    transition: all var(--transition-fast);
    overflow: hidden;
}

.backlog-card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-sm);
}

.backlog-card:active {
    cursor: grabbing;
}

.backlog-card.dragging {
    opacity: 0.4;
    transform: rotate(2deg);
}

.backlog-card-top {
    width: 4px;
    flex-shrink: 0;
}

.backlog-card-body {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    min-width: 0;
}

.backlog-card-title {
    font-weight: 500;
    font-size: var(--font-size-sm);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.backlog-card-desc {
    font-size: var(--font-size-xs);
    color: var(--color-gray-500);
    margin-top: 2px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.backlog-card-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-xs);
}

.backlog-card-tag {
    font-size: 10px;
    padding: 1px 6px;
    border: 1px solid var(--color-gray-200);
    border-radius: var(--border-radius-full);
    color: var(--color-gray-600);
    white-space: nowrap;
}

.backlog-card-actions {
    display: flex;
    align-items: center;
    padding-right: var(--spacing-xs);
}

/* Stats */
.backlog-stats {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: var(--spacing-md);
}

@media (max-width: 1024px) {
    .backlog-split {
        grid-template-columns: 1fr;
        height: auto;
    }
    
    .backlog-panel-body {
        min-height: 300px;
    }
}

/* Utility */
.btn-xs {
    padding: 2px 6px;
    font-size: var(--font-size-xs);
}