Is Liquid allowed in a Product section's Custom CSS?

[trojanmarc]

I'm trying to add the following metafield context to my product theme template and it doesn't seem to be taking:

section {background-color: {{ product.metafields.custom.color1}} }

That same code will work in a Liquid section, but not the Custom CSS section. I can not locate Shopify documentation that explicitly defines allowing or disallowing Liquid in the Custom CSS sections.

Does anyone have any tips on this?