What does these errors mean?

[JapanFoodGrocer]

I am trying to validate my HTML code using https://validator.w3.org/ and I am coming up with the following errors 

Can anybody help me with finding a solution to clear this error.

My website is https://www.japanfoodgrocer.com/

[DaisyVo]

Hi @JapanFoodGrocer ,

This is a property from the CSS Containment Module Level 3, and currently, not all browsers support it.

The container-type property is supported in modern browsers such as Chrome, Edge (version 105 and above), and Firefox. If you are using an older browser version, please consider updating it for better compatibility.

Hope this can help!

Best,

Daisy

[JapanFoodGrocer]

I am using Chrome and it is updated. However I cannot find where the code is at in my Shopify code to fix the error. How do get access to the CSS Containment Module Level 3?