:root {
    --primary-color: #3b82f6;
    --primary-dark: #2563eb;
    --secondary-color: #f3f4f6;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--secondary-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* Navigation */
.navbar {
    background: white;
    padding: 1rem 2rem;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.user-menu {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.user-info i {
    font-size: 1.2rem;
    color: var(--primary);
}

.btn-logout {
    background: var(--error-color);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    font-size: 0.85rem;
    cursor: pointer;
    transition: background-color 0.2s;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-brand i {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.nav-brand h1 {
    color: var(--text-color);
    font-size: 1.5rem;
    font-weight: 600;
}

.nav-tabs {
    display: flex;
    gap: 0.5rem;
}

.nav-tab {
    padding: 0.75rem 1.5rem;
    border: none;
    background: transparent;
    color: var(--text-light);
    cursor: pointer;
    border-radius: 0.5rem;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-tab:hover {
    background: var(--secondary-color);
    color: var(--text-color);
}

.nav-tab.active {
    background: var(--primary-color);
    color: white;
}

.active-timer {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: var(--success-color);
    color: white;
    border-radius: 0.5rem;
    font-weight: 500;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.8; }
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* Cards */
.card {
    background: white;
    border-radius: 0.75rem;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
    overflow: hidden;
}

.card-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.card-header h2 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-color);
}

.card-content {
    padding: 1.5rem;
}

.card-content.collapsed {
    display: none;
}

/* Forms */
.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-color);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

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

.btn-secondary {
    background: var(--secondary-color);
    color: var(--text-color);
}

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

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

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

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

.btn-collapse {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-light);
    padding: 0.5rem;
}

.btn-small {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* Filters */
.filters {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    align-items: center;
}

.btn-filter {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    background: white;
    color: var(--text-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-filter.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.filter-select {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background: white;
}

/* Task List */
.task-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.task-item {
    background: white;
    border-radius: 0.75rem;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    transition: transform 0.2s, box-shadow 0.2s;
}

.task-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.task-header {
    display: flex;
    align-items: center;
    justify-content: between;
    margin-bottom: 1rem;
}

.task-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-color);
    flex-grow: 1;
}

.task-status {
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
}

.task-status.todo {
    background: #f3f4f6;
    color: #4b5563;
}

.task-status.in_progress {
    background: #dbeafe;
    color: #1d4ed8;
}

.task-status.completed {
    background: #d1fae5;
    color: #065f46;
}

.task-meta {
    display: flex;
    gap: 1rem;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.task-actions {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.task-description {
    margin-bottom: 1rem;
    color: var(--text-light);
}

.task-progress {
    margin: 1rem 0;
}

.progress-bar {
    width: 100%;
    height: 0.5rem;
    background: var(--secondary-color);
    border-radius: 9999px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--success-color);
    transition: width 0.3s;
}

/* Task hierarchy */
.task-children {
    margin-left: 2rem;
    margin-top: 1rem;
    border-left: 2px solid var(--border-color);
    padding-left: 1rem;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: white;
    padding: 1.5rem;
    border-radius: 0.75rem;
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 1rem;
}

.stat-icon {
    width: 3rem;
    height: 3rem;
    border-radius: 0.75rem;
    background: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
}

.stat-content h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
    margin-bottom: 0.25rem;
}

.stat-content p {
    color: var(--text-light);
    font-size: 0.875rem;
}

/* Charts */
.charts-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
}

.chart-card {
    background: white;
    padding: 1.5rem;
    border-radius: 0.75rem;
    box-shadow: var(--shadow);
}

.chart-card h3 {
    margin-bottom: 1rem;
    color: var(--text-color);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
}

.modal.show {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: white;
    border-radius: 0.75rem;
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
}

.modal-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: between;
    align-items: center;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
}

.modal-body {
    padding: 1.5rem;
}

/* Tab Content */
.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Date Picker */
.date-picker {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    background: white;
}

/* Daily Log Styles */
.daily-summary {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.summary-item {
    text-align: center;
    padding: 1rem;
    background: var(--secondary-color);
    border-radius: 0.5rem;
}

.summary-item h4 {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.task-log {
    margin-bottom: 1.5rem;
}

.task-log h4 {
    margin-bottom: 1rem;
    color: var(--text-color);
}

.task-log-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem;
    background: var(--secondary-color);
    border-radius: 0.5rem;
    margin-bottom: 0.5rem;
}

.notes-section {
    margin-top: 2rem;
}

.notes-section textarea {
    width: 100%;
    min-height: 120px;
    padding: 1rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    resize: vertical;
}

/* Priority indicators */
.priority-high { border-left: 4px solid var(--error-color); }
.priority-medium { border-left: 4px solid var(--warning-color); }
.priority-low { border-left: 4px solid var(--success-color); }

/* Category colors */
.category-literature { background: #fef3c7; color: #92400e; }
.category-writing { background: #dbeafe; color: #1e40af; }
.category-research { background: #d1fae5; color: #065f46; }
.category-analysis { background: #e0e7ff; color: #3730a3; }
.category-methodology { background: #fce7f3; color: #be185d; }
.category-general { background: #f3f4f6; color: #374151; }

/* Text colors */
.text-error { color: var(--error-color); }
.text-warning { color: var(--warning-color); }
.text-success { color: var(--success-color); }
.text-info { color: var(--primary-color); }

/* Deadline indicators */
.deadline-overdue {
    border-left: 4px solid var(--error-color);
    background: rgba(239, 68, 68, 0.1);
}

.deadline-soon {
    border-left: 4px solid var(--warning-color);
    background: rgba(245, 158, 11, 0.1);
}

.deadline-info {
    font-size: 0.875rem;
    color: var(--text-light);
    margin-top: 0.5rem;
}

.deadline-overdue .deadline-info {
    color: var(--error-color);
    font-weight: 500;
}

.deadline-soon .deadline-info {
    color: var(--warning-color);
    font-weight: 500;
}

/* Subtask creation */
.subtask-form {
    display: none;
    margin-top: 1rem;
    padding: 1rem;
    background: var(--secondary-color);
    border-radius: 0.5rem;
    border: 2px dashed var(--border-color);
}

.subtask-form.show {
    display: block;
}

.subtask-form .form-row {
    margin-bottom: 0.5rem;
}

.subtask-form .form-group {
    margin-bottom: 0.5rem;
}

/* Task working indicator */
.task-working {
    border-left: 4px solid var(--success-color);
    background: rgba(16, 185, 129, 0.05);
}

.working-indicator {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.75rem;
    color: var(--success-color);
    font-weight: 500;
}

.working-indicator i {
    animation: pulse 2s infinite;
}

/* Analytics controls */
.analytics-controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    align-items: end;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.control-group label {
    font-weight: 500;
    color: var(--text-color);
}

.export-buttons {
    display: flex;
    gap: 0.5rem;
}

/* Detailed statistics */
.detailed-stats-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

.detailed-stats-table th,
.detailed-stats-table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.detailed-stats-table th {
    background: var(--secondary-color);
    font-weight: 600;
    color: var(--text-color);
}

.detailed-stats-table tr:hover {
    background: rgba(59, 130, 246, 0.05);
}

.stat-highlight {
    font-weight: 600;
    color: var(--primary-color);
}

.detailed-stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.stat-item h4 {
    margin-bottom: 1rem;
    color: var(--text-color);
    font-weight: 600;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    
    .navbar {
        padding: 1rem;
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-tabs {
        width: 100%;
        justify-content: center;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .charts-container {
        grid-template-columns: 1fr;
    }
    
    .task-actions {
        flex-direction: column;
    }
    
    .filters {
        flex-direction: column;
        align-items: stretch;
    }
}

/* Loading and Empty States */
.loading {
    text-align: center;
    padding: 2rem;
    color: var(--text-light);
}

.empty-state {
    text-align: center;
    padding: 3rem 2rem;
    color: var(--text-light);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--border-color);
}

/* Loading indicator */
.global-loader {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 2rem;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    z-index: 1002;
    opacity: 0;
    transform: translateX(-50%) translateY(-10px);
    transition: all 0.3s ease;
    pointer-events: none;
}

.global-loader.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.loader-spinner {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.fade-in {
    animation: fadeIn 0.3s ease-out;
}

/* Category Management */
.category-management {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-top: 1rem;
}

.category-form h3,
.category-list h3 {
    margin: 0 0 1rem 0;
    color: var(--text-primary);
    font-size: 1.1rem;
}

.category-list {
    max-height: 300px;
    overflow-y: auto;
}

.category-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem;
    margin: 0.5rem 0;
    border: 1px solid var(--border-light);
    border-radius: 6px;
    background: var(--bg-secondary);
}

.category-item:hover {
    background: var(--bg-hover);
    border-color: var(--border-hover);
}

.category-info {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex: 1;
}

.category-color {
    width: 20px;
    height: 20px;
    border-radius: 3px;
    border: 1px solid var(--border-light);
}

.category-details {
    flex: 1;
}

.category-name {
    font-weight: 500;
    color: var(--text-primary);
    margin: 0 0 0.25rem 0;
}

.category-description {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin: 0;
}

.category-default {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-style: italic;
}

.category-actions {
    display: flex;
    gap: 0.5rem;
}

.btn-category {
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-category.edit {
    background: var(--primary-light);
    color: var(--primary);
}

.btn-category.edit:hover {
    background: var(--primary);
    color: white;
}

.btn-category.delete {
    background: var(--error-light);
    color: var(--error);
}

.btn-category.delete:hover {
    background: var(--error);
    color: white;
}

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

@media (max-width: 768px) {
    .category-management {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .category-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.75rem;
    }
    
    .category-actions {
        align-self: flex-end;
    }
}

/* Productivity Score Explanation */
.productivity-explanation {
    max-width: 100%;
}

.explanation-section {
    margin-bottom: 2rem;
}

.explanation-section h4 {
    color: var(--text-primary);
    margin-bottom: 0.75rem;
    font-size: 1.1rem;
}

.formula-box {
    background: var(--bg-secondary);
    border: 1px solid var(--border-light);
    border-radius: 6px;
    padding: 1rem;
    margin: 1rem 0;
    text-align: center;
}

.formula-box strong {
    color: var(--primary);
    font-size: 1.1rem;
    display: block;
    margin-bottom: 0.5rem;
}

.formula-box small {
    color: var(--text-muted);
    font-style: italic;
}

.score-ranges {
    display: grid;
    gap: 0.75rem;
    margin-top: 1rem;
}

.score-range {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem;
    border-radius: 6px;
    border-left: 4px solid;
}

.score-range.excellent {
    background: rgba(16, 185, 129, 0.1);
    border-left-color: var(--success);
}

.score-range.good {
    background: rgba(59, 130, 246, 0.1);
    border-left-color: var(--primary);
}

.score-range.fair {
    background: rgba(245, 158, 11, 0.1);
    border-left-color: var(--warning);
}

.score-range.low {
    background: rgba(239, 68, 68, 0.1);
    border-left-color: var(--error);
}

.range-label {
    font-weight: bold;
    min-width: 80px;
    font-size: 0.9rem;
}

.range-desc {
    color: var(--text-secondary);
    flex: 1;
}

.improvement-tips {
    margin: 1rem 0;
    padding-left: 1.5rem;
}

.improvement-tips li {
    margin-bottom: 0.75rem;
    line-height: 1.5;
    color: var(--text-secondary);
}

.improvement-tips strong {
    color: var(--text-primary);
}

@media (max-width: 768px) {
    .score-range {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
    }
    
    .range-label {
        min-width: auto;
    }
}

/* Chart Empty States */
.chart-empty-state {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    text-align: center;
    background: var(--bg-secondary);
    border: 1px dashed var(--border-light);
    border-radius: 8px;
    margin: 1rem 0;
}

.empty-chart-content {
    max-width: 300px;
    padding: 1rem;
}

.empty-chart-content i {
    display: block;
    color: var(--text-muted);
}

.empty-chart-content p {
    margin: 0.5rem 0;
    line-height: 1.5;
}

.empty-chart-content p:first-of-type {
    color: var(--text-primary);
    margin-bottom: 0.75rem;
}

.empty-chart-content p:last-of-type {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Chart Grouping Info */
.chart-grouping-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-style: italic;
}

.chart-grouping-info i {
    color: var(--primary);
}

.chart-grouping-info #currentGrouping {
    font-weight: 500;
    color: var(--text-primary);
}