root = Card([nextMeetingHeader, attendeeList, joinButtons])
nextMeetingTitle = "Project Sync"
nextMeetingTime = "Tomorrow at 10:00 AM"
nextMeetingHeader = CardHeader(title: nextMeetingTitle, subtitle: nextMeetingTime)
attendeeList = ListBlock(items: [ListItem(title: "Alice"), ListItem(title: "Bob"), ListItem(title: "Charlie")])
joinBtn = Button(label: "Join Call", action: ["https://example.com/join"])
joinButtons = Buttons(buttons: [joinBtn], direction: "row")