[HTML5 spec for hr is to apply `overflow: hidden`](https://html.spec.whatwg.org/multipage/rendering.html#the-hr-element-2), but [normalize is currently applying `overflow: visible`](https://github.com/necolas/normalize.css/blob/master/normalize.css#L56). Please either remove what appears to be an unneeded override of a now-uniform default style or apply the expected overflow: hidden.