// Page topbar — title + subtitle + actions slot.
function Topbar({ title, subtitle, children }) {
  return (
    <div className="topbar">
      <div>
        <h1>{title}</h1>
        {subtitle && <div className="topbar-sub">{subtitle}</div>}
      </div>
      <div className="topbar-actions">{children}</div>
    </div>
  );
}

Object.assign(window, { Topbar });