Here is a snippet that has six different button animation for text links, it was designed by Riccardo Zanutta. The first one is a ghost button with a shadow, when you hover over it the border colour fills the button covering the shadow and it feels like the button is pushed down. In the second one, a different colour moves in from the corners to the centre of the button. In the third one, we have the left, right border and on hover, they move in closer to the centre and the top and button. For the fourth one, when you hover over it the border comes into view. With number five when you hover over it there is a wiggle animation for the button. For the last one when you hover over the ghost button a solid colour fills in and we get rounded corners for the button.
If you are having trouble with the pen, try the archived copy on GitHub