Classes are a native way for devs to use reusable selectors.
Class attribute has native js API for add, remove, toggle.
Attributes like x-style are not valid attributes. The only possible way here would be using data-* attribute
Stylify doesn't use space for selector because it needs the selector to be complete for further optimization like chaining a button to padding:4px_8px and mangling .padding:4px_8px => .a