Price and stock per colour/size (variant pricing)

If a product has options (e.g. colour, size), the product editor lets you set a separate price, old price, and stock for each combination (e.g. "Red / L") next to the options block — leaving a combination's field blank means it inherits the product's overall price/stock. Up to 200 combinations are supported. Once any combination gets a stock number, the whole product switches to tracking stock at the combination level.