I get what you're trying to do, because i did something similar with forms in PHP, but the dependencies and functions are too much... especially for production use.
my advice is i would maybe focus on doing less things more efficiently. Or even better, offering a way like TW Bootstrap does, where you can choose your components and it spits out what you want.
I wouldn't use 95% of the functionality of this code so having thousands of lines of code that i will never use is very unattractive for me when im thinking about optimization, debugging, etc.
ADDITION: And i mean something that compiles your main ojjs js file, BEFORE the plugins. For example: I would never need any of the css functionality in this but it's included in the core. That's what i meant. I'm aware you have the ability to add 'plugins'. My idea of choosing parts was to choose parts within the current 'core' code.
However, it looks like you are investing a lot of time into this and it's not a bad idea, so i applaud that. Just think it needs a little organizing/re-thinking in some aspects. Good luck :)
As for the CSS support it is actually quite elegant. Maybe 100 lines with full support for '&:nested' selectors, and nestable '@media' query support.
One thing that I've been considering is right now 40-50% of the oj.js filesize is support for the Form Elements (TextBox, ListBox, CheckBox,Button) and the "collection" elements (BulletList,NumberList,Table). I'm still considering pulling these out of the core and making them plugins. The issue is they manipulate the basic tags (input,textarea,table,ul,etc) so they seem pretty fundamental. Is that something you would want?