root = Card([header, form, socialProof], "card", "column", "m")
header = CardHeader("The Product Weekly", "One actionable product insight in your inbox, every Tuesday.")
form = Form("newsletter-signup", formButtons, [emailField])
emailField = FormControl("Email address", emailInput, "We'll never share your email.")
emailInput = Input("email", "you@example.com", "email")
formButtons = Buttons([subscribeBtn])
subscribeBtn = Button("Subscribe", null, "primary")
socialProof = TextContent("Join 12,000+ product people.", "small")