Change from using 'this' pointer to using unique IDs for group toggling:
- Generate unique IDs for each group (group-0, group-1, etc.)
- Pass group ID to toggleGroup() function instead of DOM element
- Use getElementById() and previousElementSibling to find elements
- Add error handling with console.error for missing elements
- Add console.log statements for debugging
This approach is more reliable than relying on inline onclick handlers
with 'this' keyword, especially when the HTML is dynamically generated.