Sticky add-to-cart

Customize → Product → Show sticky add-to-cart on mobile (default ON).

Behavior

• Hidden by default
• Reveals when the main ATC button scrolls out of viewport (Intersection Observer based, no scroll math)
• Hides when the main ATC re-enters viewport
• Only on mobile (≤749px); never shows on desktop

Contents

• Product title (truncated to fit one line)
• Current variant price
• Add to cart button (uses your custom Add to cart text label from Buy buttons block)

Variant changes

Variant changes (color/size pick) update both the in-page button and the sticky button simultaneously. Price reflects the selected variant. Out-of-stock state disables both.

Tips

• Don't hide it on long PDPs — it's an effortless conversion lifter.
• For brands with a strict minimal aesthetic, the sticky bar honours your radius / button settings — it's still on-brand.