root = Card([header, amount, dueDate, paymentBtn])

header = CardHeader("Invoice #INV-2024-071", "Freelance Website Redesign — Client Billing")

amount = Card([amountLabel, amountValue], "sunk")
amountLabel = TextContent("Amount Due", "small-heavy")
amountValue = Heading("$1,250.00 USD", "h2")

dueDate = TextContent("**Due date:** June 30, 2025", "default")

paymentBtn = Buttons([payNow])
payNow = Button("Pay Now", null, "primary", null, "large")