A conversion-optimized, fully customizable dynamic popup section designed to display targeted checkout upsells, offering configurable positions (Centered Modal with blur background overlay or Floating Bottom Bar/Mobile slide sheet), multiple behavioral triggers (exit intent cursor detection, scroll thresholds, page-load delays, add-to-cart clicks), live variant selectors, AJAX reload-less ATC submissions, stock scarcity alerts, and session-persistent countdown timers, all fully scoped to prevent style overrides.