root = Card([header, description, form])
header = CardHeader("Weekly Product Newsletter", "Stay updated with the latest product insights")
description = TextContent("Get a curated digest of product launches, feature deep-dives, and industry trends delivered to your inbox every Monday.")
form = Form("newsletter-signup", formButtons, [emailField])
emailField = FormControl("Email address", emailInput, "We respect your privacy. Unsubscribe anytime.")
emailInput = Input("email", "you@company.com", "email")
formButtons = Buttons([subscribeBtn])
subscribeBtn = Button("Subscribe", null, "primary")