Online Store 2.0 Theme Support
Back in Stock now supports Online Store 2.0 themes. OS2 themes allow users to customize visual elements and extensions in the new Shopify Theme Editor. You can change the color, font size, margins and many other attributes of the Back in Stock button directly in the theme editor without leaving the Shopify Admin. A page preview will update immediately after changes are made.
When Back in Stock is installed in a store, it detects if the theme is OS2 compatible and automatically set the corresponding theme integration. You can check the current theme integration in Settings menu, Theme integration submenu.
But if you already had Back in Stock installed and updated your store to a OS2 compatible theme, you must manually select the Online Store 2.0, otherwise changes in Back in Stock app won't affect the BIS button (read the section below for more details why this happens).
Finally, just click in the link Setup and customize Back in Stock button in Shopify Theme Editor to finish the setup. It will redirect you to Shopify Theme Editor and add the Back in Stock button in your OS2 theme.
How it works
Basically, the OS2 integration will keep the Back in Stock settings synchronized with the button in the theme. Every time a change is detected in Back in Stock app, a specific metafield that is used by the BIS button to fetch the last widget version is updated.