root = Card([header, amountCard, dueCard, paySection])
header = CardHeader("Invoice #INV-2024-118", "Acme Studio · Design retainer")
amountCard = Card([amountHeading, amountText], "sunk", "column", "xs")
amountHeading = TextContent("Amount due", "small")
amountText = TextContent("$4,850.00 USD", "large-heavy")
dueCard = Card([dueHeading, dueText], "sunk", "column", "xs")
dueHeading = TextContent("Due date", "small")
dueText = TextContent("September 30, 2024", "large")
paySection = Card([payBtn, noteCallout], "clear", "column", "m")
payBtn = Button("Pay now", null, "primary")
noteCallout = TextCallout("neutral", "Payment methods", "Pay by bank transfer, card, or PayPal. A 2.9% fee applies to card payments.")