Advanced — for merchants comfortable with HTML and CSS.
Two slots
Custom HTML
Injected into a defined region of the drawer (above items, below items, etc.). Use for custom callouts, embeds, or merch-specific copy.
Custom CSS
Scoped to .ia-cart-root. Use specific selectors so you don't break the editor preview.
Best practices
Test in preview before publishing — broken CSS can hide the entire drawer.
Use specific class selectors, not generic tags.
.ia-cart-root .my-banneris safer thandiv.Avoid
!importantunless you really need to override a base style.Don't inject scripts that fetch external resources synchronously — it slows the drawer.
When to ask for help
If your custom CSS works in preview but not on the live storefront, the issue is usually theme CSS specificity. Reach out to support with a screenshot and your snippet.