:root {
    /* Color Palette */
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #8b5cf6;
    --accent-color: #ec4899;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;

    /* Dark Theme Colors */
    --bg-primary: #0f0f23;
    --bg-secondary: #1a1a2e;
    --bg-tertiary: #16213e;
    --bg-card: rgba(255, 255, 255, 0.05);
    --bg-hover: rgba(255, 255, 255, 0.1);

    /* Text Colors */
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    /* Border & Shadow */
    --border-color: rgba(255, 255, 255, 0.1);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --glow: 0 0 20px rgba(99, 102, 241, 0.3);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    color: var(--text-primary);
    overflow: hidden;
    height: 100vh;
}

/* App Container */
.app-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
}

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg) var(--spacing-xl);
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.header-left {
    display: flex;
    align-items: baseline;
    gap: var(--spacing-md);
}

.app-title {
    font-size: 1.75rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.app-subtitle {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 400;
}

.header-controls {
    display: flex;
    gap: var(--spacing-md);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 0.625rem 1.25rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-base);
    font-family: inherit;
}

.btn-icon {
    font-size: 1rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md), var(--glow);
}

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

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

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

.btn-danger:hover {
    background: #dc2626;
    transform: translateY(-2px);
}

.icon-btn {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 1rem;
    transition: all var(--transition-base);
}

.icon-btn:hover {
    background: var(--bg-hover);
    border-color: var(--primary-color);
}

/* Main Content */
.main-content {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 320px;
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.sidebar-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.sidebar-header h2 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.search-input {
    width: 100%;
    padding: 0.625rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    font-family: inherit;
    transition: all var(--transition-base);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.timeline-list {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-sm);
}

/* Custom Scrollbar */
.timeline-list::-webkit-scrollbar {
    width: 8px;
}

.timeline-list::-webkit-scrollbar-track {
    background: transparent;
}

.timeline-list::-webkit-scrollbar-thumb {
    background: var(--bg-hover);
    border-radius: var(--radius-lg);
}

.timeline-list::-webkit-scrollbar-thumb:hover {
    background: var(--border-color);
}

/* Timeline Item */
.timeline-item {
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
}

.timeline-item:hover {
    background: var(--bg-hover);
    border-color: var(--primary-color);
    transform: translateX(4px);
}

.timeline-item.active {
    background: rgba(99, 102, 241, 0.1);
    border-color: var(--primary-color);
    box-shadow: var(--glow);
}

/* Drag and Drop Feedback */
.timeline-item.dragging {
    opacity: 0.5;
    background-color: var(--bg-hover);
    border: 1px dashed var(--text-muted);
}

.timeline-item.drag-over-top::before {
    content: '';
    position: absolute;
    top: -5px;
    /* Halfway in the 8px margin gap */
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--accent-color);
    box-shadow: 0 0 8px var(--accent-color);
    z-index: 10;
    pointer-events: none;
}

.timeline-item.drag-over-bottom::after {
    content: '';
    position: absolute;
    bottom: -5px;
    /* Halfway in the 8px margin gap */
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--accent-color);
    box-shadow: 0 0 8px var(--accent-color);
    z-index: 10;
    pointer-events: none;
}

.timeline-item-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
}

.timeline-color {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    flex-shrink: 0;
}

.timeline-item-name {
    font-weight: 500;
    font-size: 0.9375rem;
    flex: 1;
}

.timeline-item-category {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.timeline-item-actions {
    display: flex;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-sm);
}

.timeline-item-actions button {
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.timeline-item-actions button:hover {
    color: var(--text-primary);
    border-color: var(--primary-color);
}

/* Canvas Area */
.canvas-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    position: relative;
}

.canvas-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
}

.canvas-controls {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.zoom-level {
    margin-left: var(--spacing-sm);
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.view-info {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.canvas-wrapper {
    flex: 1;
    position: relative;
    overflow: hidden;
}

#timelineCanvas {
    width: 100%;
    height: 100%;
    cursor: grab;
}

#timelineCanvas:active {
    cursor: grabbing;
}

/* Minimap */
.minimap-container {
    position: absolute;
    bottom: 20px;
    right: 20px;
    width: 200px;
    height: 100px;
    background: rgba(15, 15, 35, 0.8);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

#minimapCanvas {
    width: 100%;
    height: 100%;
}

/* Empty State */
.empty-state {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.empty-state p {
    font-size: 0.875rem;
    max-width: 400px;
}

.empty-state.hidden {
    display: none;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    animation: modalSlideIn var(--transition-base);
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

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

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

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

.modal-body {
    padding: var(--spacing-lg);
    overflow-y: auto;
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
}

/* Form Elements */
.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.form-input {
    width: 100%;
    padding: 0.625rem;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    font-family: inherit;
    transition: all var(--transition-base);
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

textarea.form-input {
    resize: vertical;
    min-height: 80px;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
}

.color-picker {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.color-picker input[type="color"] {
    width: 60px;
    height: 40px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    background: var(--bg-primary);
}

.color-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.file-input {
    width: 100%;
    padding: 0.625rem;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.875rem;
    cursor: pointer;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        max-width: 280px;
    }

    .header-controls {
        flex-wrap: wrap;
    }

    .app-subtitle {
        display: none;
    }
}