* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --danger: #ef4444;
    --success: #22c55e;
    --warning: #f59e0b;
    --border: #475569;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: auto;
}

.app {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    background: var(--bg-secondary);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.header h1 i {
    color: var(--accent);
}

.header-right {
    display: flex;
    gap: 0.75rem;
}

/* Buttons */
.btn {
    padding: 0.625rem 1rem;
    border: none;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s;
}

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

.btn-primary:hover {
    background: var(--accent-hover);
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border);
}

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

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

.btn-danger:hover {
    background: #dc2626;
}

/* Board */
.board {
    flex: 1;
    padding: 1.5rem;
    display: flex;
    gap: 1.5rem;
    overflow-x: auto;
    min-height: calc(100vh - 80px);
}

/* Column */
.column {
    background: var(--bg-secondary);
    border-radius: 0.75rem;
    min-width: 320px;
    max-width: 320px;
    display: flex;
    flex-direction: column;
    max-height: calc(100vh - 120px);
}

.column-header {
    padding: 1rem;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.column-title {
    font-size: 1rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.column-count {
    background: var(--bg-card);
    padding: 0.25rem 0.5rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.column-actions {
    display: flex;
    gap: 0.25rem;
}

.column-actions button {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 0.25rem;
    transition: all 0.2s;
}

.column-actions button:hover {
    background: var(--bg-card);
    color: var(--text-primary);
}

.column-body {
    flex: 1;
    padding: 0.75rem;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.add-card-btn {
    background: transparent;
    border: 2px dashed var(--border);
    color: var(--text-secondary);
    padding: 0.75rem;
    border-radius: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    transition: all 0.2s;
}

.add-card-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Card */
.card {
    background: var(--bg-card);
    border-radius: 0.5rem;
    padding: 1rem;
    cursor: grab;
    transition: transform 0.2s, box-shadow 0.2s;
    border: 1px solid transparent;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    border-color: var(--border);
}

.card.dragging {
    opacity: 0.5;
    cursor: grabbing;
}

.card-title {
    font-weight: 500;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.card-description {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    line-height: 1.5;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.card-tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.5rem;
    border-radius: 0.25rem;
    font-weight: 500;
    text-transform: uppercase;
}

.tag-urgent { background: rgba(239, 68, 68, 0.2); color: var(--danger); }
.tag-bug { background: rgba(245, 158, 11, 0.2); color: var(--warning); }
.tag-feature { background: rgba(34, 197, 94, 0.2); color: var(--success); }
.tag-default { background: rgba(59, 130, 246, 0.2); color: var(--accent); }

.card-date {
    font-size: 0.75rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-secondary);
    border-radius: 0.75rem;
    width: 100%;
    max-width: 500px;
    margin: 1rem;
    border: 1px solid var(--border);
}

.modal-header {
    padding: 1.25rem;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.close-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 0.375rem;
    transition: all 0.2s;
}

.close-btn:hover {
    background: var(--bg-card);
    color: var(--text-primary);
}

.modal-body {
    padding: 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.modal-footer {
    padding: 1.25rem;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: flex-end;
    gap: 0.75rem;
}

/* Form Elements */
.input-field {
    width: 100%;
    padding: 0.75rem 1rem;
    background: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    color: var(--text-primary);
    font-size: 0.875rem;
    font-family: inherit;
    transition: border-color 0.2s;
}

.input-field:focus {
    outline: none;
    border-color: var(--accent);
}

.input-field::placeholder {
    color: var(--text-secondary);
}

.textarea {
    min-height: 120px;
    resize: vertical;
}

.card-meta {
    display: flex;
    gap: 1rem;
}

.card-meta .input-field {
    flex: 1;
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--bg-card);
}

/* Drag and Drop */
.column-body.drag-over {
    background: rgba(59, 130, 246, 0.1);
    border-radius: 0.5rem;
}

/* Responsive */
@media (max-width: 768px) {
    .header {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    
    .header-right {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .column {
        min-width: 280px;
        max-width: 280px;
    }
}