3 Column Preview Card Component using HTML and CSS

Looks good. One small change I would recommend to remove the jink (the button causing the section jitter) would be to do the following:

1. In the dormant state of the button instead of making the button's border = border: none; make it the same as the hover effect but the border color is transparent: border: 2px solid transparent.
2. Add a transition for a smoother hover effect: transition: all 300ms ease;