/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    overflow: hidden;
    padding: 30px;
}

/* Header Styles */
.header {
    text-align: center;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 2px solid #f0f0f0;
}

.header h1 {
    color: #4a5568;
    font-size: 2.8rem;
    margin-bottom: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
}

.header h1 i {
    color: #667eea;
}

.subtitle {
    color: #718096;
    font-size: 1.2rem;
    font-weight: 300;
}

/* Stats Panel */
.stats-panel {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.stat-card {
    background: linear-gradient(135deg, #f6f8ff 0%, #edf2f7 100%);
    border-radius: 15px;
    padding: 25px;
    display: flex;
    align-items: center;
    gap: 20px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border: 1px solid #e2e8f0;
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.stat-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.8rem;
}

.stat-info h3 {
    color: #4a5568;
    font-size: 1rem;
    margin-bottom: 5px;
    font-weight: 600;
}

.stat-value {
    color: #2d3748;
    font-size: 2.2rem;
    font-weight: 700;
}

/* Input Section */
.input-section {
    background: #f7fafc;
    border-radius: 15px;
    padding: 30px;
    margin-bottom: 40px;
    border: 1px solid #e2e8f0;
}

.input-group {
    display: flex;
    gap: 15px;
    margin-bottom: 25px;
    flex-wrap: wrap;
}

#task-input {
    flex: 1;
    min-width: 300px;
    padding: 15px 20px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

#task-input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

#priority-select {
    padding: 15px 20px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 1rem;
    background: white;
    cursor: pointer;
    min-width: 180px;
}

.btn-primary {
    padding: 15px 30px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    display: flex;
    align-items: center;
    gap: 10px;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

.filter-section {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 10px 20px;
    background: white;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-btn.active {
    background: #667eea;
    color: white;
    border-color: #667eea;
}

.filter-btn:hover:not(.active) {
    background: #f7fafc;
    border-color: #667eea;
}

/* Tasks Container */
.tasks-container {
    margin-bottom: 40px;
}

.tasks-container h2 {
    color: #4a5568;
    font-size: 1.8rem;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.tasks-list {
    min-height: 200px;
    background: #f7fafc;
    border-radius: 15px;
    padding: 20px;
    border: 1px solid #e2e8f0;
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: #718096;
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: 20px;
    color: #cbd5e0;
}

.empty-state h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: #4a5568;
}

.task-item {
    background: white;
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 15px;
    border-left: 4px solid #e2e8f0;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.task-item:hover {
    transform: translateX(5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.task-item.priority-high {
    border-left-color: #fc8181;
}

.task-item.priority-medium {
    border-left-color: #f6ad55;
}

.task-item.priority-low {
    border-left-color: #68d391;
}

.task-item.completed {
    opacity: 0.7;
    background: #f0fff4;
}

.task-checkbox {
    width: 24px;
    height: 24px;
    cursor: pointer;
    accent-color: #48bb78;
}

.task-content {
    flex: 1;
}

.task-text {
    font-size: 1.1rem;
    margin-bottom: 5px;
    color: #2d3748;
}

.task-item.completed .task-text {
    text-decoration: line-through;
    color: #718096;
}

.task-meta {
    display: flex;
    gap: 15px;
    font-size: 0.9rem;
    color: #718096;
}

.task-priority {
    padding: 3px 10px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.priority-high .task-priority {
    background: #fed7d7;
    color: #c53030;
}

.priority-medium .task-priority {
    background: #feebc8;
    color: #c05621;
}

.priority-low .task-priority {
    background: #c6f6d5;
    color: #276749;
}

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

.task-btn {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    border: none;
    background: #edf2f7;
    color: #4a5568;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.task-btn:hover {
    background: #e2e8f0;
    transform: scale(1.1);
}

.task-btn.delete:hover {
    background: #fed7d7;
    color: #c53030;
}

/* Features Section */
.features-section {
    margin-bottom: 40px;
}

.features-section h2 {
    color: #4a5568;
    font-size: 1.8rem;
    margin-bottom: 25px;
    display: flex;
    align-items: center;
    gap: 10px;
}

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

.feature-card {
    background: linear-gradient(135deg, #f6f8ff 0%, #edf2f7 100%);
    border-radius: 15px;
    padding: 25px;
    text-align: center;
    transition: transform 0.3s ease;
    border: 1px solid #e2e8f0;
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-card i {
    font-size: 2.5rem;
    color: #667eea;
    margin-bottom: 15px;
}

.feature-card h3 {
    color: #4a5568;
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.feature-card p {
    color: #718096;
    font-size: 0.95rem;
    line-height: 1.5;
}

/* Footer */
.footer {
    text-align: center;
    padding-top: 30px;
    border-top: 2px solid #f0f0f0;
    color: #718096;
}

.footer p {
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 5px;
}

.footer p i {
    color: #fc8181;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 30px;
    flex-wrap: wrap;
}

.footer-links a {
    color: #667eea;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: #764ba2;
}

/* Notification */
.notification {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: #48bb78;
    color: white;
    padding: 15px 25px;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    transform: translateY(100px);
    opacity: 0;
    transition: transform 0.3s ease, opacity 0.3s ease;
    z-index: 1000;
}

.notification.show {
    transform: translateY(0);
    opacity: 1;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 20px;
    }

    .header h1 {
        font-size: 2rem;
    }

    .input-group {
        flex-direction: column;
    }

    #task-input {
        min-width: 100%;
    }

    .stats-panel {
        grid-template-columns: 1fr;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .task-item {
        flex-direction: column;
        align-items: flex-start;
    }

    .task-actions {
        align-self: flex-end;
    }
}

/* Animation for task addition */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.task-item {
    animation: fadeIn 0.3s ease-out;
}