The attribute fit is not implemented.

[yangchenyun]

The doc mentions the fit attribute will apply --layout-fit to the #maincontent, but this promise is not implemented here.

Would either mention it in the doc to ask the user imports the iron-positioning in iron-flex-layout-classes.html or we put it in the stylesheet in scope :host ::content .fit { ... }

[blasten]

That's true. We should either remove that from the docs or add that behavior back to the element. PR welcome.