Square button with rounded shape on hover : <p>I designed a call to action box. The idea is to add on hover a rounded shape. This shape need to slide in smoothly. Does anyone an idea or an example how to program this?</p>

<p><a href="https://i.stack.imgur.com/hp4Gi.png" rel="nofollow noreferrer">Normal state on the left. On the right the hover state. </a></p>

<p>Thanks for now.</p>

<p>Arjan</p>
