* {
    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;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    backdrop-filter: blur(10px);
}

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

.header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    font-weight: 700;
}

.header p {
    opacity: 0.9;
    font-size: 1.1rem;
}

.add-task-section {
    padding: 30px;
    border-bottom: 1px solid #eee;
}

.task-input-group {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.task-input {
    padding: 15px;
    border: 2px solid #e1e5e9;
    border-radius: 12px;
    font-size: 16px;
    transition: all 0.3s ease;
    outline: none;
}

.task-input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.datetime-group {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.datetime-input {
    flex: 1;
    min-width: 200px;
    padding: 12px;
    border: 2px solid #e1e5e9;
    border-radius: 12px;
    font-size: 14px;
    transition: all 0.3s ease;
    outline: none;
}

.datetime-input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.add-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    transform: translateY(0);
}

.add-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.3);
}

.add-btn:active {
    transform: translateY(0);
}

.tasks-section {
    padding: 30px;
}

.filter-buttons {
    display: flex;
    gap: 10px;
    margin-bottom: 25px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 8px 16px;
    border: 2px solid #e1e5e9;
    background: white;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 14px;
    font-weight: 500;
}

.filter-btn.active {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border-color: transparent;
}

.filter-btn:hover {
    transform: translateY(-1px);
}

.tasks-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.task-item {
    background: white;
    border: 2px solid #f0f0f0;
    border-radius: 15px;
    padding: 20px;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.task-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
    border-color: #667eea;
}

.task-item.completed {
    opacity: 0.7;
    background: #f8f9fa;
}

.task-item.completed .task-text {
    text-decoration: line-through;
    color: #6c757d;
}

.task-header {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 10px;
}

.task-checkbox {
    width: 24px;
    height: 24px;
    border: 2px solid #ddd;
    border-radius: 6px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.task-checkbox.checked {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-color: transparent;
    color: white;
}

.task-text {
    flex: 1;
    font-size: 16px;
    font-weight: 500;
    line-height: 1.4;
}

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

.action-btn {
    padding: 6px 12px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 12px;
    font-weight: 500;
    transition: all 0.3s ease;
}

.edit-btn {
    background: #ffc107;
    color: #212529;
}

.edit-btn:hover {
    background: #e0a800;
    transform: translateY(-1px);
}

.delete-btn {
    background: #dc3545;
    color: white;
}

.delete-btn:hover {
    background: #c82333;
    transform: translateY(-1px);
}

.task-datetime {
    font-size: 14px;
    color: #6c757d;
    margin-top: 8px;
    display: flex;
    align-items: center;
    gap: 15px;
}

.datetime-badge {
    background: #e9ecef;
    padding: 4px 8px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 500;
}

.datetime-badge.overdue {
    background: #ffebee;
    color: #c62828;
}

.datetime-badge.today {
    background: #e8f5e8;
    color: #2e7d32;
}

.edit-form {
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid #eee;
}

.edit-input {
    width: 100%;
    padding: 12px;
    border: 2px solid #e1e5e9;
    border-radius: 8px;
    margin-bottom: 10px;
    font-size: 14px;
    outline: none;
}

.edit-input:focus {
    border-color: #667eea;
}

.edit-datetime-group {
    display: flex;
    gap: 10px;
    margin-bottom: 10px;
    flex-wrap: wrap;
}

.edit-datetime-input {
    flex: 1;
    min-width: 150px;
    padding: 10px;
    border: 2px solid #e1e5e9;
    border-radius: 8px;
    font-size: 14px;
    outline: none;
}

.edit-datetime-input:focus {
    border-color: #667eea;
}

.save-btn {
    background: #28a745;
    color: white;
    margin-right: 10px;
}

.save-btn:hover {
    background: #218838;
}

.cancel-btn {
    background: #6c757d;
    color: white;
}

.cancel-btn:hover {
    background: #5a6268;
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: #6c757d;
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 20px;
    opacity: 0.5;
}

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

.stats {
    display: flex;
    justify-content: space-around;
    padding: 20px;
    background: #f8f9fa;
    margin-bottom: 20px;
    border-radius: 12px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: #667eea;
}

.stat-label {
    font-size: 0.9rem;
    color: #6c757d;
    font-weight: 500;
}

@media (max-width: 768px) {
    .container {
        margin: 10px;
        border-radius: 15px;
    }

    .header {
        padding: 20px;
    }

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

    .add-task-section, .tasks-section {
        padding: 20px;
    }

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

    .datetime-input {
        min-width: auto;
    }

    .task-header {
        flex-wrap: wrap;
        gap: 10px;
    }

    .task-actions {
        width: 100%;
        justify-content: flex-end;
    }
}