What class is responsible for such animation in UIKit?

Question

UIkit

Hello.
On the official website of UIKit, there are links in the menu - when you hover over these links, a small bar appears at the bottom of the text, and it smoothly goes to the right.
Screenshots -

So, in fact, what class is responsible for such a smooth appearance of the strip?

Answer 1

Hello. class uk-button-text , read the UIkit documentation in Russian , yet the 3rd version is not completely in Russian, but the documentation is all, and with perspectives for the future...