diff --git a/v4 b/v4
new file mode 100644
index 0000000..a339ad0
--- /dev/null
+++ b/v4
@@ -0,0 +1,604 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Notification Manager</title>
+    
+    <!-- React & ReactDOM -->
+    <script crossorigin src="https://unpkg.com/react@18/umd/react.development.js"></script>
+    <script crossorigin src="https://unpkg.com/react-dom@18/umd/react-dom.development.js"></script>
+    
+    <!-- Babel for JSX -->
+    <script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
+    
+    <!-- Tailwind CSS -->
+    <script src="https://cdn.tailwindcss.com"></script>
+    
+    <!-- Lucide Icons -->
+    <script src="https://unpkg.com/lucide@latest"></script>
+
+    <style>
+        /* Custom Scrollbar */
+        ::-webkit-scrollbar {
+            width: 8px;
+            height: 8px;
+        }
+        ::-webkit-scrollbar-track {
+            background: #f1f5f9; 
+        }
+        ::-webkit-scrollbar-thumb {
+            background: #cbd5e1; 
+            border-radius: 4px;
+        }
+        ::-webkit-scrollbar-thumb:hover {
+            background: #94a3b8; 
+        }
+        
+        .toggle-checkbox:checked {
+            right: 0;
+            border-color: #68D391;
+        }
+        .toggle-checkbox:checked + .toggle-label {
+            background-color: #68D391;
+        }
+        
+        .accordion-content {
+            transition: max-height 0.3s ease-in-out, opacity 0.3s ease-in-out;
+            max-height: 0;
+            opacity: 0;
+            overflow: hidden;
+        }
+        .accordion-content.expanded {
+            max-height: 1000px;
+            opacity: 1;
+        }
+        
+        /* Animation for section entry */
+        @keyframes fadeIn {
+            from { opacity: 0; transform: translateY(10px); }
+            to { opacity: 1; transform: translateY(0); }
+        }
+        .animate-fade-in {
+            animation: fadeIn 0.5s ease-out forwards;
+        }
+
+        /* Popover animation */
+        .popover-enter {
+            opacity: 0;
+            transform: scale(0.95) translateY(-5px);
+        }
+        .popover-enter-active {
+            opacity: 1;
+            transform: scale(1) translateY(0);
+            transition: opacity 150ms ease-out, transform 150ms ease-out;
+        }
+    </style>
+</head>
+<body class="bg-slate-50 text-slate-800 font-sans antialiased">
+    <div id="root"></div>
+
+    <script type="text/babel">
+        const { useState, useEffect, useRef, useMemo } = React;
+
+        // --- Data Definitions ---
+
+        // 0. Define User Devices and Emails (The new dimension)
+        const USER_DEVICES = [
+            { id: 'dev_1', name: 'iPhone 15 Pro' },
+            { id: 'dev_2', name: 'iPad Air' }
+        ];
+
+        const USER_EMAILS = [
+            { id: 'em_1', name: 'j.doe@company.com' },
+            { id: 'em_2', name: 'johnny@gmail.com' }
+        ];
+
+        // 1. Define the Categories and their Events
+        // UPDATED: Channels now store arrays of IDs instead of booleans
+        const CATEGORY_DEFINITIONS = {
+            cat_trips: {
+                id: 'cat_trips',
+                name: 'My Trips',
+                description: 'Notifications related to your travel history and active journeys.',
+                enabled: true,
+                channels: { app: ['dev_1', 'dev_2'], email: [] },
+                events: [
+                    { id: 'evt_in', name: 'Tap In', description: 'When you start a journey', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: [] } },
+                    { id: 'evt_out', name: 'Tap Out', description: 'When you end a journey', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: [] } },
+                    { id: 'evt_miss_out', name: 'Missing Tap Out', description: 'Alert when you forget to check out', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: ['em_1'] } },
+                    { id: 'evt_recalc', name: 'Trip Recalculated', description: 'Price corrections', enabled: true, channels: { app: ['dev_1'], email: ['em_1', 'em_2'] } },
+                ]
+            },
+            cat_service: {
+                id: 'cat_service',
+                name: 'My Service Messages',
+                description: 'Bundled events regarding service and account status.',
+                enabled: true,
+                channels: { app: ['dev_1', 'dev_2'], email: ['em_1'] },
+                events: [
+                    { id: 'evt_miss_out', name: 'Missing Tap Out', description: 'Alert when you forget to check out', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: ['em_1'] } },
+                    { id: 'evt_refund', name: 'Refund Processed', description: 'Updates on your refund requests', enabled: true, channels: { app: ['dev_1'], email: ['em_1'] } },
+                ]
+            },
+            cat_products: {
+                id: 'cat_products',
+                name: 'My Products',
+                description: 'Updates about your subscriptions and card validity.',
+                enabled: false,
+                channels: { app: ['dev_1', 'dev_2'], email: ['em_1', 'em_2'] },
+                events: [
+                    { id: 'evt_sub_renew', name: 'Subscription Renewal', description: 'Monthly renewal alerts', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: ['em_1'] } },
+                    { id: 'evt_card_exp', name: 'Card Expiry', description: 'Warning before card expires', enabled: true, channels: { app: [], email: ['em_1'] } },
+                ]
+            },
+            cat_disruptions: {
+                id: 'cat_disruptions',
+                name: 'Disruptions',
+                description: 'Real-time alerts about delays on your favorite routes.',
+                enabled: true,
+                channels: { app: ['dev_1', 'dev_2'], email: [] },
+                events: [
+                    { id: 'evt_delay', name: 'Delays > 15min', description: 'Significant delays', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: [] } },
+                    { id: 'evt_cancelled', name: 'Train Cancelled', description: 'Cancellations on route', enabled: true, channels: { app: ['dev_1', 'dev_2'], email: [] } },
+                    { id: 'evt_maintenance', name: 'Planned Maintenance', description: 'Future work alerts', enabled: false, channels: { app: [], email: ['em_1'] } },
+                ]
+            },
+            cat_newsletter: {
+                id: 'cat_newsletter',
+                name: 'Newsletter',
+                description: 'Stay updated with our latest news and offers.',
+                enabled: true,
+                channels: { app: [], email: ['em_2'] },
+                events: [
+                    { id: 'evt_weekly', name: 'Weekly Digest', description: 'Summary of your travels', enabled: true, channels: { app: [], email: ['em_2'] } },
+                    { id: 'evt_offers', name: 'Partner Offers', description: 'Exclusive deals', enabled: true, channels: { app: [], email: ['em_2'] } }
+                ]
+            }
+        };
+
+        // 2. Define Resource Groups
+        const RESOURCE_GROUPS_CONFIG = [
+            {
+                id: 'rg_cards',
+                title: 'Travel Cards',
+                icon: 'credit-card',
+                type: 'selector', // Requires a dropdown to select specific resource
+                resources: [
+                    { id: 't1', name: 'Personal OV-chipkaart (**** 9021)', type: 'Personal' },
+                    { id: 't2', name: 'NS Business Card (**** 3321)', type: 'Business' },
+                    { id: 't3', name: 'Anonymous Travel Card (**** 1100)', type: 'Anonymous' }
+                ],
+                categoryIds: ['cat_trips', 'cat_service', 'cat_products']
+            },
+            {
+                id: 'rg_updates',
+                title: 'Trip Updates',
+                icon: 'train',
+                type: 'static', // Single block, no selection
+                resources: [{ id: 'global_updates', name: 'Trip Updates', type: 'System' }],
+                categoryIds: ['cat_disruptions']
+            },
+            {
+                id: 'rg_marketing',
+                title: 'Marketing',
+                icon: 'megaphone',
+                type: 'static', 
+                resources: [{ id: 'global_marketing', name: 'Marketing', type: 'System' }],
+                categoryIds: ['cat_newsletter']
+            }
+        ];
+
+        // 3. Generator for Initial State
+        const generateInitialState = () => {
+            const state = {};
+            
+            RESOURCE_GROUPS_CONFIG.forEach(group => {
+                group.resources.forEach(resource => {
+                    // Create deep copy of categories for this specific resource
+                    const resourceCategories = group.categoryIds.map(catId => 
+                        JSON.parse(JSON.stringify(CATEGORY_DEFINITIONS[catId]))
+                    );
+                    state[resource.id] = resourceCategories;
+                });
+            });
+            
+            return state;
+        };
+
+        // --- Components ---
+
+        const ToggleSwitch = ({ checked, onChange, disabled }) => (
+            <div className={`relative inline-block w-10 mr-2 align-middle select-none transition duration-200 ease-in ${disabled ? 'opacity-50 cursor-not-allowed' : ''}`}>
+                <input 
+                    type="checkbox" 
+                    className={`toggle-checkbox absolute block w-5 h-5 rounded-full bg-white border-4 appearance-none cursor-pointer transition-all duration-300 ${checked ? 'right-0 border-green-500' : 'left-0 border-gray-300'}`} 
+                    checked={checked} 
+                    onChange={(e) => !disabled && onChange(e.target.checked)}
+                    disabled={disabled}
+                />
+                <label 
+                    className={`toggle-label block overflow-hidden h-5 rounded-full cursor-pointer transition-colors duration-300 ${checked ? 'bg-green-500' : 'bg-gray-300'}`}
+                ></label>
+            </div>
+        );
+
+        // New Component: MultiSelect Dropdown for Channels
+        const ChannelMultiSelect = ({ options, selectedIds = [], onChange, disabled }) => {
+            const [isOpen, setIsOpen] = useState(false);
+            const containerRef = useRef(null);
+
+            // Handle click outside to close
+            useEffect(() => {
+                const handleClickOutside = (event) => {
+                    if (containerRef.current && !containerRef.current.contains(event.target)) {
+                        setIsOpen(false);
+                    }
+                };
+                document.addEventListener('mousedown', handleClickOutside);
+                return () => document.removeEventListener('mousedown', handleClickOutside);
+            }, []);
+
+            const handleToggleOption = (id) => {
+                let newSelected;
+                if (selectedIds.includes(id)) {
+                    newSelected = selectedIds.filter(existingId => existingId !== id);
+                } else {
+                    newSelected = [...selectedIds, id];
+                }
+                onChange(newSelected);
+            };
+
+            const handleSelectAll = () => {
+                if (selectedIds.length === options.length) {
+                    onChange([]);
+                } else {
+                    onChange(options.map(o => o.id));
+                }
+            };
+
+            const selectionLabel = useMemo(() => {
+                if (selectedIds.length === 0) return "Off";
+                if (selectedIds.length === options.length) return "All";
+                return `${selectedIds.length} / ${options.length}`;
+            }, [selectedIds, options]);
+
+            const isActive = selectedIds.length > 0;
+
+            return (
+                <div className="relative inline-block" ref={containerRef}>
+                    <button 
+                        onClick={() => !disabled && setIsOpen(!isOpen)}
+                        disabled={disabled}
+                        className={`
+                            h-8 px-3 rounded-md text-xs font-semibold flex items-center gap-2 border transition-all
+                            ${disabled ? 'opacity-40 cursor-not-allowed bg-slate-100 border-slate-200 text-slate-400' : 
+                              isActive ? 'bg-blue-50 border-blue-200 text-blue-700 hover:bg-blue-100' : 'bg-white border-slate-300 text-slate-600 hover:bg-slate-50'}
+                        `}
+                    >
+                        <span>{selectionLabel}</span>
+                        <i data-lucide="chevron-down" className={`w-3 h-3 transition-transform ${isOpen ? 'rotate-180' : ''}`}></i>
+                    </button>
+
+                    {isOpen && !disabled && (
+                        <div className="absolute top-full left-1/2 -translate-x-1/2 mt-2 w-48 bg-white border border-slate-200 rounded-lg shadow-xl z-50 p-2 animate-fade-in origin-top">
+                             <div 
+                                onClick={handleSelectAll}
+                                className="px-2 py-1.5 text-xs font-bold text-slate-500 uppercase cursor-pointer hover:bg-slate-50 rounded flex justify-between items-center mb-1"
+                            >
+                                <span>Select All</span>
+                                <div className={`w-3 h-3 border rounded ${selectedIds.length === options.length ? 'bg-slate-500 border-slate-500' : 'border-slate-300'}`}></div>
+                            </div>
+                            <div className="space-y-1">
+                                {options.map(option => {
+                                    const isSelected = selectedIds.includes(option.id);
+                                    return (
+                                        <div 
+                                            key={option.id}
+                                            onClick={() => handleToggleOption(option.id)}
+                                            className={`
+                                                flex items-center gap-3 px-2 py-2 rounded cursor-pointer text-sm
+                                                ${isSelected ? 'bg-blue-50 text-blue-700' : 'text-slate-700 hover:bg-slate-50'}
+                                            `}
+                                        >
+                                            <div className={`
+                                                w-4 h-4 rounded border flex items-center justify-center transition-colors
+                                                ${isSelected ? 'bg-blue-500 border-blue-500' : 'bg-white border-slate-300'}
+                                            `}>
+                                                {isSelected && <svg className="w-2.5 h-2.5 text-white" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={4}><path strokeLinecap="round" strokeLinejoin="round" d="M5 13l4 4L19 7" /></svg>}
+                                            </div>
+                                            <span className="truncate">{option.name}</span>
+                                        </div>
+                                    );
+                                })}
+                            </div>
+                        </div>
+                    )}
+                </div>
+            );
+        };
+
+        const ResourceSelector = ({ resources, selectedId, onSelect, label, icon }) => {
+            const selectedResource = resources.find(r => r.id === selectedId);
+            const [isOpen, setIsOpen] = useState(false);
+
+            return (
+                <div className="relative mb-6 z-20">
+                    <button 
+                        onClick={() => setIsOpen(!isOpen)}
+                        className="w-full md:w-96 flex items-center justify-between bg-white border border-slate-200 hover:border-blue-400 px-4 py-3 rounded-xl shadow-sm transition-all text-left"
+                    >
+                        <div className="flex items-center gap-3">
+                            <div className="bg-blue-100 p-2 rounded-full text-blue-600">
+                                <i data-lucide={icon || "layers"}></i>
+                            </div>
+                            <div>
+                                <div className="font-bold text-slate-800">{selectedResource?.name}</div>
+                                <div className="text-xs text-slate-500">{selectedResource?.type}</div>
+                            </div>
+                        </div>
+                        <i data-lucide="chevron-down" className={`text-slate-400 transition-transform ${isOpen ? 'rotate-180' : ''}`}></i>
+                    </button>
+
+                    {isOpen && (
+                        <div className="absolute top-full mt-2 w-full md:w-96 bg-white border border-slate-100 rounded-xl shadow-xl overflow-hidden animate-fade-in-down z-50">
+                            {resources.map(res => (
+                                <div 
+                                    key={res.id}
+                                    onClick={() => { onSelect(res.id); setIsOpen(false); }}
+                                    className={`px-4 py-3 cursor-pointer hover:bg-slate-50 flex items-center gap-3 border-b border-slate-50 last:border-0 ${res.id === selectedId ? 'bg-blue-50/50' : ''}`}
+                                >
+                                    <div className={`w-2 h-2 rounded-full ${res.id === selectedId ? 'bg-blue-500' : 'bg-slate-300'}`}></div>
+                                    <div className="text-sm font-medium text-slate-700">{res.name}</div>
+                                </div>
+                            ))}
+                        </div>
+                    )}
+                </div>
+            );
+        };
+
+        const NotificationMatrix = ({ data, onUpdate }) => {
+            const [expandedCategories, setExpandedCategories] = useState({});
+
+            const toggleExpand = (catId) => {
+                setExpandedCategories(prev => ({
+                    ...prev,
+                    [catId]: !prev[catId]
+                }));
+            };
+
+            // Shared logic: Updates all matching events in all categories
+            const updateWithSync = (newData, targetCatId, targetEventId, updateFn) => {
+                 // 1. Identify what we are targeting
+                 // If targetEventId is null, we are targeting a Category change that might affect multiple events
+                 // If targetEventId is present, we are targeting that specific event type
+                 
+                 let targetEventIds = new Set();
+                 
+                 if (targetEventId) {
+                     targetEventIds.add(targetEventId);
+                 } else if (targetCatId) {
+                     const cat = data.find(c => c.id === targetCatId);
+                     if (cat) cat.events.forEach(e => targetEventIds.add(e.id));
+                 }
+
+                 return data.map(cat => {
+                     // Apply Category Level changes
+                     let newCat = { ...cat };
+                     if (targetCatId && cat.id === targetCatId) {
+                         newCat = updateFn(cat, 'category'); 
+                     }
+
+                     // Apply Event Level changes (propagate to all events matching IDs)
+                     const newEvents = newCat.events.map(evt => {
+                         if (targetEventIds.has(evt.id)) {
+                             return updateFn(evt, 'event');
+                         }
+                         return evt;
+                     });
+
+                     newCat.events = newEvents;
+                     return newCat;
+                 });
+            };
+
+            const handleCategoryToggle = (catId, val) => {
+                const updated = updateWithSync(data, catId, null, (item, type) => {
+                    if (type === 'category') return { ...item, enabled: val };
+                    if (type === 'event') return { ...item, enabled: val };
+                    return item;
+                });
+                onUpdate(updated);
+            };
+
+            const handleCategoryChannel = (catId, channel, newSelectedIds) => {
+                const updated = updateWithSync(data, catId, null, (item, type) => {
+                    // Update the channel with the new array of selected IDs
+                    if (type === 'category') return { ...item, channels: { ...item.channels, [channel]: newSelectedIds } };
+                    if (type === 'event') return { ...item, channels: { ...item.channels, [channel]: newSelectedIds } };
+                    return item;
+                });
+                onUpdate(updated);
+            };
+
+            const handleEventToggle = (catId, evtId, val) => {
+                const updated = updateWithSync(data, null, evtId, (item, type) => {
+                    if (type === 'event') return { ...item, enabled: val };
+                    return item;
+                });
+                onUpdate(updated);
+            };
+
+            const handleEventChannel = (catId, evtId, channel, newSelectedIds) => {
+                const updated = updateWithSync(data, null, evtId, (item, type) => {
+                    if (type === 'event') return { ...item, channels: { ...item.channels, [channel]: newSelectedIds } };
+                    return item;
+                });
+                onUpdate(updated);
+            };
+
+            return (
+                <div className="bg-white rounded-2xl shadow-sm border border-slate-200 overflow-hidden mb-8">
+                    <div className="grid grid-cols-12 gap-4 p-4 bg-slate-100 border-b border-slate-200 text-xs font-bold text-slate-500 uppercase tracking-wider">
+                        <div className="col-span-6 md:col-span-5 pl-2">Category / Event</div>
+                        <div className="col-span-2 text-center">Status</div>
+                        <div className="col-span-4 md:col-span-5 flex justify-around">
+                            <span>App Push</span>
+                            <span>Email</span>
+                        </div>
+                    </div>
+
+                    <div className="divide-y divide-slate-100">
+                        {data.map(cat => {
+                            const isExpanded = !!expandedCategories[cat.id];
+                            return (
+                                <div key={cat.id} className="group">
+                                    <div className={`grid grid-cols-12 gap-4 p-4 items-center transition-colors hover:bg-slate-50 ${isExpanded ? 'bg-slate-50/80' : ''}`}>
+                                        <div className="col-span-6 md:col-span-5 flex items-center gap-3">
+                                            <button 
+                                                onClick={() => toggleExpand(cat.id)}
+                                                className="p-1 rounded hover:bg-slate-200 text-slate-400 hover:text-slate-600 transition-colors"
+                                            >
+                                                <i data-lucide={isExpanded ? "chevron-down" : "chevron-right"} className="w-5 h-5"></i>
+                                            </button>
+                                            <div className="flex flex-col">
+                                                <span className="font-bold text-slate-800 text-base">{cat.name}</span>
+                                                <span className="text-xs text-slate-500 hidden md:block">{cat.description}</span>
+                                            </div>
+                                        </div>
+                                        <div className="col-span-2 flex justify-center">
+                                            <ToggleSwitch checked={cat.enabled} onChange={(v) => handleCategoryToggle(cat.id, v)} />
+                                        </div>
+                                        <div className="col-span-4 md:col-span-5 flex justify-around items-center">
+                                            <ChannelMultiSelect 
+                                                options={USER_DEVICES}
+                                                selectedIds={cat.channels.app} 
+                                                onChange={(ids) => handleCategoryChannel(cat.id, 'app', ids)} 
+                                                disabled={!cat.enabled} 
+                                            />
+                                            <ChannelMultiSelect 
+                                                options={USER_EMAILS}
+                                                selectedIds={cat.channels.email} 
+                                                onChange={(ids) => handleCategoryChannel(cat.id, 'email', ids)} 
+                                                disabled={!cat.enabled} 
+                                            />
+                                        </div>
+                                    </div>
+                                    <div className={`accordion-content bg-slate-50/50 ${isExpanded ? 'expanded' : ''}`}>
+                                        <div className="pl-0 md:pl-0 border-t border-slate-100/50">
+                                            {cat.events.map((evt) => (
+                                                <div key={evt.id} className={`grid grid-cols-12 gap-4 py-3 px-4 items-center border-b border-slate-100 last:border-0 ${!cat.enabled ? 'opacity-40 pointer-events-none' : ''}`}>
+                                                    <div className="col-span-6 md:col-span-5 pl-12 flex flex-col justify-center relative">
+                                                        <div className="absolute left-6 top-0 bottom-1/2 w-px bg-slate-200 -z-10 h-full"></div>
+                                                        <div className="absolute left-6 top-1/2 w-4 h-px bg-slate-200 -z-10"></div>
+                                                        <span className="text-sm font-medium text-slate-700">{evt.name}</span>
+                                                        <span className="text-[10px] text-slate-400 md:hidden">{evt.description}</span>
+                                                    </div>
+                                                    <div className="col-span-2 flex justify-center">
+                                                        <ToggleSwitch checked={evt.enabled} onChange={(v) => handleEventToggle(cat.id, evt.id, v)} disabled={!cat.enabled} />
+                                                    </div>
+                                                    <div className="col-span-4 md:col-span-5 flex justify-around items-center">
+                                                        <ChannelMultiSelect 
+                                                            options={USER_DEVICES}
+                                                            selectedIds={evt.channels.app} 
+                                                            onChange={(ids) => handleEventChannel(cat.id, evt.id, 'app', ids)} 
+                                                            disabled={!cat.enabled || !evt.enabled} 
+                                                        />
+                                                        <ChannelMultiSelect 
+                                                            options={USER_EMAILS}
+                                                            selectedIds={evt.channels.email} 
+                                                            onChange={(ids) => handleEventChannel(cat.id, evt.id, 'email', ids)} 
+                                                            disabled={!cat.enabled || !evt.enabled} 
+                                                        />
+                                                    </div>
+                                                </div>
+                                            ))}
+                                        </div>
+                                    </div>
+                                </div>
+                            );
+                        })}
+                    </div>
+                </div>
+            );
+        };
+
+        const ResourceGroupSection = ({ config, settings, onUpdateSettings }) => {
+            const [selectedResourceId, setSelectedResourceId] = useState(config.resources[0].id);
+            const currentData = settings[selectedResourceId];
+
+            const handleMatrixUpdate = (newData) => {
+                onUpdateSettings(selectedResourceId, newData);
+            };
+
+            return (
+                <div className="mb-12 animate-fade-in">
+                    <div className="flex items-center gap-3 mb-6 border-b border-slate-200 pb-2">
+                        <i data-lucide={config.icon} className="text-blue-500 w-6 h-6"></i>
+                        <h2 className="text-xl font-bold text-slate-800 tracking-tight">{config.title}</h2>
+                    </div>
+
+                    {config.type === 'selector' && (
+                        <ResourceSelector 
+                            resources={config.resources} 
+                            selectedId={selectedResourceId} 
+                            onSelect={setSelectedResourceId}
+                            label={`Select ${config.title}`}
+                            icon={config.icon}
+                        />
+                    )}
+
+                    <NotificationMatrix 
+                        data={currentData} 
+                        onUpdate={handleMatrixUpdate} 
+                    />
+                </div>
+            );
+        };
+
+        const App = () => {
+            const [settings, setSettings] = useState(generateInitialState());
+
+            // Initialize icons
+            useEffect(() => {
+                if (window.lucide) window.lucide.createIcons();
+            });
+
+            const handleSettingsUpdate = (resourceId, newData) => {
+                setSettings(prev => ({
+                    ...prev,
+                    [resourceId]: newData
+                }));
+            };
+
+            return (
+                <div className="min-h-screen p-4 md:p-12 max-w-5xl mx-auto">
+                    {/* Main Header */}
+                    <div className="mb-12 text-center md:text-left">
+                        <h1 className="text-4xl font-extrabold text-slate-900 mb-3 tracking-tight">Notification Center</h1>
+                        <p className="text-lg text-slate-500">Manage all your communication preferences in one place.</p>
+                    </div>
+
+                    {/* Iterate over Resource Groups */}
+                    {RESOURCE_GROUPS_CONFIG.map(group => (
+                        <ResourceGroupSection 
+                            key={group.id} 
+                            config={group} 
+                            settings={settings}
+                            onUpdateSettings={handleSettingsUpdate}
+                        />
+                    ))}
+
+                    <div className="mt-12 pt-8 border-t border-slate-200 text-center text-xs text-slate-400">
+                        <p>Preferences are auto-saved. Shared event types are synchronized within their resource group.</p>
+                    </div>
+                </div>
+            );
+        };
+
+        const root = ReactDOM.createRoot(document.getElementById('root'));
+        root.render(<App />);
+    </script>
+</body>
+</html>
\ No newline at end of file
