Macro class 

class!() { /* proc-macro */ }

The arguments are list of expressions, separated by space, all of them need to be compatible with String::from()

The idea is to write in a very similar way of CSS, but can be compile time checked, also can provide code completion nicely.

Example

class: class!(card card_compact w_64 h_64 bg_base_300 shadow_xl text_center hover(bg_base_200) hover(scale_105)),