Changing CSS variables with CMS dynamic embed?

I’m trying to replicate the “Blue Dream Effects and Attributes” section on this page: Blue Dream Weed Strain Information | Leafly

Basically I’d like my client to be able to enter a number value into the CMS and have that value pulled as a width percentage for a CSS transition effect. Since the embed code can call the CMS I figure it might offer a solution.

Any thoughts?