The way to get new elements is to have a use-case, show current methods to get what you want or get close, and show why it is important a new element be introduced to solve this purpose. Even better now that Web Components exist, make a polyfill of the element so it can be played with an explored.
Simply asking for an element because you want some CSS property to get used more won’t go anywhere. That provides no reason to drive browser developers to implement a new element.
If you feel so strongly about the new property, instead of asking for an element to try and get people to use it, evangelize it. Write a blog post. Look into conversations on different networks and chime in when you see a problem where the property solves the case. Write to newsletters and let them know your blog post exists and ask to get included in a future letter to subscribers.