:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --info-color: #06b6d4;
    
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    
    --border-color: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px 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);
    
    --radius: 12px;
    --radius-sm: 8px;
}

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

body {
    font-family: 'Inter', 'Segoe UI', system-ui, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    color: var(--text-primary);
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    animation: fadeInUp 0.8s ease-out;
}

/* Header Styles */
.app-header {
    background: var(--bg-primary);
    border-radius: var(--radius);
    padding: 30px;
    margin-bottom: 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.logo {
    font-size: 2.5em;
    font-weight: 700;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo i {
    font-size: 1.2em;
}

.search-bar {
    position: relative;
    width: 100%;
    max-width: 400px;
}

.search-bar input {
    width: 100%;
    padding: 14px 45px 14px 20px;
    border: 2px solid var(--border-color);
    border-radius: 50px;
    font-size: 16px;
    transition: all 0.3s ease;
    background: var(--bg-secondary);
}

.search-bar input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
    transform: translateY(-1px);
}

.search-bar i {
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-light);
}

/* Quick Stats */
.quick-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 24px;
}

.stat-item {
    background: var(--bg-primary);
    padding: 24px;
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    gap: 16px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

.stat-item:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-color);
    color: white;
    font-size: 24px;
}

.stat-icon.completed {
    background: var(--success-color);
}

.stat-icon.pending {
    background: var(--warning-color);
}

.stat-number {
    display: block;
    font-size: 28px;
    font-weight: 700;
    color: var(--text-primary);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 500;
}

/* Form Styles */
.task-form {
    background: var(--bg-primary);
    padding: 30px;
    border-radius: var(--radius);
    margin-bottom: 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    animation: slideInDown 0.6s ease-out;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group.full-width {
    grid-column: 1 / -1;
}

.form-group label {
    margin-bottom: 8px;
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 14px;
}

.form-group input,
.form-group select,
.form-group textarea {
    padding: 14px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 16px;
    transition: all 0.3s ease;
    background: var(--bg-secondary);
}

.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(99, 102, 241, 0.1);
    transform: translateY(-1px);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    padding: 14px 28px;
    border-radius: var(--radius-sm);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

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

/* Controls */
.controls-section {
    background: var(--bg-primary);
    padding: 24px;
    border-radius: var(--radius);
    margin-bottom: 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.view-controls {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.view-btn {
    padding: 10px 20px;
    border: 2px solid var(--border-color);
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

.view-btn.active,
.view-btn:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    transform: translateY(-1px);
}

.filter-controls {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.filter-select {
    padding: 10px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Tasks List */
.tasks-container {
    background: var(--bg-primary);
    border-radius: var(--radius);
    margin-bottom: 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    overflow: hidden;
}

.todo-list {
    list-style: none;
    min-height: 200px;
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-light);
}

.empty-state i {
    font-size: 48px;
    margin-bottom: 16px;
    opacity: 0.5;
}

.todo-item {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 16px;
    transition: all 0.3s ease;
    animation: slideInRight 0.4s ease-out;
}

.todo-item:last-child {
    border-bottom: none;
}

.todo-item:hover {
    background: var(--bg-secondary);
    transform: translateX(5px);
}

.todo-item.completed {
    opacity: 0.7;
    background: var(--bg-tertiary);
}

.todo-item.overdue {
    border-left: 4px solid var(--danger-color);
}

.todo-checkbox {
    width: 22px;
    height: 22px;
    border: 2px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    flex-shrink: 0;
}

.todo-checkbox.checked {
    background: var(--success-color);
    border-color: var(--success-color);
    color: white;
}

.todo-content {
    flex: 1;
}

.todo-title {
    font-weight: 600;
    margin-bottom: 4px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.todo-item.completed .todo-title {
    text-decoration: line-through;
    color: var(--text-light);
}

.todo-description {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 8px;
}

.todo-meta {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.todo-category,
.todo-priority,
.todo-due-date {
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 500;
}

.todo-category.work { background: #dbeafe; color: #1e40af; }
.todo-category.personal { background: #f3e8ff; color: #7e22ce; }
.todo-category.shopping { background: #fef3c7; color: #d97706; }
.todo-category.health { background: #dcfce7; color: #166534; }
.todo-category.education { background: #fce7f3; color: #be185d; }
.todo-category.finance { background: #ffedd5; color: #ea580c; }

.todo-priority.high { background: #fecaca; color: #dc2626; }
.todo-priority.medium { background: #fef3c7; color: #d97706; }
.todo-priority.low { background: #d1fae5; color: #065f46; }

.todo-due-date.overdue {
    background: var(--danger-color);
    color: white;
}

.todo-actions {
    display: flex;
    gap: 8px;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.todo-item:hover .todo-actions {
    opacity: 1;
}

.action-btn {
    padding: 8px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
}

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

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

.action-btn:hover {
    transform: scale(1.1);
}

/* Progress Section */
.progress-section {
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

.progress-card {
    background: var(--bg-primary);
    padding: 30px;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.progress-stats {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 24px;
}

.progress-bar {
    flex: 1;
    height: 12px;
    background: var(--bg-tertiary);
    border-radius: 10px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--success-color), var(--primary-color));
    border-radius: 10px;
    transition: width 1s ease-in-out;
    position: relative;
    overflow: hidden;
}

.progress-fill::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.4), transparent);
    animation: shimmer 2s infinite;
}

.progress-percentage {
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color);
    min-width: 60px;
}

.progress-details {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
}

.progress-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
}

.progress-label {
    color: var(--text-secondary);
    font-weight: 500;
}

.progress-value {
    font-weight: 700;
    color: var(--primary-color);
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
    z-index: 1000;
    animation: fadeIn 0.3s ease;
}

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

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius);
    padding: 0;
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    animation: modalSlideIn 0.3s ease;
    box-shadow: var(--shadow-lg);
}

.modal-header {
    padding: 24px 24px 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.modal-header h3 {
    color: var(--text-primary);
    font-size: 1.5em;
}

.close-btn {
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--text-light);
    transition: color 0.3s ease;
}

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

#edit-form {
    padding: 0 24px 24px;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

.modal-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
    margin-top: 24px;
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
    padding: 12px 24px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 500;
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    transform: translateY(-1px);
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: scale(0.8) translateY(-20px);
    }
    to {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(400%); }
}

@keyframes bounceIn {
    0% {
        opacity: 0;
        transform: scale(0.3);
    }
    50% {
        opacity: 1;
        transform: scale(1.05);
    }
    70% {
        transform: scale(0.9);
    }
    100% {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes slideOutLeft {
    to {
        opacity: 0;
        transform: translateX(-100%);
    }
}

/* Task completion animation */
.todo-item.fade-out {
    animation: slideOutLeft 0.4s ease forwards;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    .header-content {
        flex-direction: column;
        align-items: stretch;
    }
    
    .logo {
        justify-content: center;
        font-size: 2em;
    }
    
    .quick-stats {
        grid-template-columns: 1fr;
    }
    
    .form-grid {
        grid-template-columns: 1fr;
    }
    
    .controls-section {
        flex-direction: column;
        align-items: stretch;
    }
    
    .view-controls {
        justify-content: center;
    }
    
    .filter-controls {
        justify-content: center;
    }
    
    .todo-item {
        flex-direction: column;
        align-items: stretch;
        gap: 12px;
    }
    
    .todo-actions {
        opacity: 1;
        justify-content: center;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .modal-actions {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .app-header,
    .task-form,
    .controls-section,
    .progress-card {
        padding: 20px;
    }
    
    .logo {
        font-size: 1.8em;
    }
    
    .view-btn {
        padding: 8px 16px;
        font-size: 14px;
    }
}

/* Dark mode support */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #1a1a1a;
        --bg-secondary: #2d2d2d;
        --bg-tertiary: #3d3d3d;
        --text-primary: #ffffff;
        --text-secondary: #a0a0a0;
        --text-light: #666666;
        --border-color: #404040;
    }
    
    body {
        background: linear-gradient(135deg, #2d3748 0%, #4a5568 100%);
    }
}