:root {
    --primary: #7269ef;
    --secondary: #7a7f9a;
    --success: #06d6a0;
    --danger: #ef476f;
    --warning: #ffd166;
    --info: #118ab2;
    --light: #f8f9fa;
    --dark: #212529;
    --background: #f5f7fb;
    --card-bg: #ffffff;
    --text-primary: #2c2c2c;
    --text-secondary: #6c757d;
    --border-color: #e6e6e6;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --background: #1a1a2e;
    --card-bg: #16213e;
    --text-primary: #f0f0f0;
    --text-secondary: #a0a0a0;
    --border-color: #2d3748;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    transition: var(--transition);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding: 20px;
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.header-content h1 {
    color: var(--primary);
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 5px;
}

.header-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.theme-toggle {
    cursor: pointer;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--light);
    border-radius: 50%;
    transition: var(--transition);
}

.theme-toggle:hover {
    background: var(--primary);
    color: white;
}

.main-content {
    display: flex;
    gap: 20px;
}

.sidebar {
    width: 250px;
    background: var(--card-bg);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
    height: fit-content;
}

.sidebar-section {
    margin-bottom: 25px;
}

.sidebar-section h3 {
    font-size: 0.9rem;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 15px;
    letter-spacing: 0.5px;
}

.category-item, .filter-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px;
    border-radius: 8px;
    margin-bottom: 8px;
    cursor: pointer;
    transition: var(--transition);
}

.category-item:hover, .filter-item:hover {
    background: rgba(114, 105, 239, 0.1);
}

.category-item.active, .filter-item.active {
    background: var(--primary);
    color: white;
}

.category-item i, .filter-item i {
    width: 18px;
    text-align: center;
}

.task-manager {
    flex: 1;
}

.task-input-panel {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

.input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 15px;
}

#taskInput {
    flex: 1;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    background: var(--card-bg);
    color: var(--text-primary);
}

#taskInput:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(114, 105, 239, 0.2);
}

.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 12px 20px;
    cursor: pointer;
    font-weight: 500;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 5px;
}

.btn-primary:hover {
    background: #6159d3;
    transform: translateY(-2px);
}

.task-options {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.option-group {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.option-group label {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.option-group input, .option-group select {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--card-bg);
    color: var(--text-primary);
}

.task-stats {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
}

.stat-item {
    flex: 1;
    background: var(--card-bg);
    border-radius: 12px;
    padding: 15px;
    text-align: center;
    box-shadow: var(--shadow);
}

.stat-number {
    display: block;
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary);
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.task-list-container {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
}

.task-list-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.task-list-header h3 {
    color: var(--text-primary);
}

.sort-options select {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--card-bg);
    color: var(--text-primary);
}

#taskList {
    list-style: none;
}

.task-item {
    background: var(--card-bg);
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    gap: 15px;
    border-left: 4px solid var(--secondary);
    transition: var(--transition);
    animation: fadeIn 0.3s ease;
}

.task-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

.task-item.priority-high {
    border-left-color: var(--danger);
}

.task-item.priority-medium {
    border-left-color: var(--warning);
}

.task-item.priority-low {
    border-left-color: var(--success);
}

.task-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.task-content {
    flex: 1;
}

.task-text {
    font-size: 1rem;
    margin-bottom: 5px;
    word-break: break-word;
}

.task-text.completed {
    text-decoration: line-through;
    color: var(--text-secondary);
}

.task-meta {
    display: flex;
    gap: 15px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.task-meta span {
    display: flex;
    align-items: center;
    gap: 5px;
}

.task-actions {
    display: flex;
    gap: 10px;
}

.task-actions button {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1rem;
    color: var(--text-secondary);
    transition: var(--transition);
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.edit-btn:hover {
    background: rgba(17, 138, 178, 0.1);
    color: var(--info);
}

.delete-btn:hover {
    background: rgba(239, 71, 111, 0.1);
    color: var(--danger);
}

.complete-btn:hover {
    background: rgba(6, 214, 160, 0.1);
    color: var(--success);
}

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

.modal-content {
    background-color: var(--card-bg);
    margin: 5% auto;
    padding: 0;
    border-radius: 12px;
    width: 90%;
    max-width: 500px;
    box-shadow: 0 5px 25px rgba(0, 0, 0, 0.2);
    animation: slideIn 0.3s ease;
}

.modal-header {
    padding: 15px 20px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h3 {
    color: var(--text-primary);
}

.close-modal {
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
}

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

.modal-body {
    padding: 20px;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.form-group input, .form-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--card-bg);
    color: var(--text-primary);
}

.form-row {
    display: flex;
    gap: 15px;
}

.form-row .form-group {
    flex: 1;
}

.modal-footer {
    padding: 15px 20px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 10px;
}

.btn-secondary {
    background: var(--secondary);
    color: white;
    border: none;
    border-radius: 6px;
    padding: 10px 15px;
    cursor: pointer;
    transition: var(--transition);
}

.btn-secondary:hover {
    background: #6c757d;
}

/* Alert Styles */
.alert {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 15px 20px;
    border-radius: 8px;
    color: white;
    display: flex;
    align-items: center;
    gap: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
    z-index: 1100;
    animation: slideInRight 0.3s ease, fadeOut 0.5s ease 2.5s forwards;
    max-width: 350px;
}

.alert-success {
    background: var(--success);
}

.alert-error {
    background: var(--danger);
}

.alert-warning {
    background: var(--warning);
    color: var(--dark);
}

.alert-info {
    background: var(--info);
}

.alert i {
    font-size: 1.2rem;
}

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

@keyframes slideIn {
    from { transform: translateY(-50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

@keyframes slideInRight {
    from { transform: translateX(100px); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

@keyframes fadeOut {
    from { opacity: 1; }
    to { opacity: 0; visibility: hidden; }
}

/* Responsive Design */
@media (max-width: 900px) {
    .main-content {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
    }
    
    .task-options {
        flex-direction: column;
    }
    
    .task-stats {
        flex-wrap: wrap;
    }
    
    .stat-item {
        flex: 1 0 calc(50% - 15px);
    }
}

@media (max-width: 600px) {
    .container {
        padding: 10px;
    }
    
    header {
        flex-direction: column;
        text-align: center;
        gap: 15px;
    }
    
    .input-group {
        flex-direction: column;
    }
    
    .task-item {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .task-actions {
        align-self: flex-end;
    }
    
    .form-row {
        flex-direction: column;
        gap: 0;
    }
    
    .stat-item {
        flex: 1 0 100%;
    }
}