Adding a strikethrough for sold out items (using app)

[LindStuart]

We are using an app (Prime Swatches) to link related variants, and it's working great – except that it doesn't have any option to indicate whether a color is sold out.

These is creating a pretty bad user experience. Can anyone help me code in a way to add a strikethrough or grayed out overlay to the colors that are sold out? I contacted the app developer but they have not been helpful... thanks in advance!

https://weathermanumbrella.com/products/stick-umbrella-black

[ThePrimeWeb]

Unfortunately, app code is not accessible and cannot be modified by anyone other than the app developer.

[LindStuart]

Thanks – I thought there might be a way to do it without accessing their code.