JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <ul class="thumb-list">
        <li>
            <a href=""><img  src="https://lh4.googleusercontent.com/-ae0Q_J_FRHo/AAAAAAAAAAI/AAAAAAAAAH0/JAgZxJY6Bb4/photo.jpg" alt="BlaBla"></a>
        </li>
        <li>
            <a href=""><img  src="https://lh3.googleusercontent.com/-xG41LLlqjq8/AAAAAAAAAAI/AAAAAAAAASY/bv7wy3udbVg/photo.jpg" alt="BlaBla"></a>
        </li>
        <li>
            <a href=""><img  src="https://pbs.twimg.com/profile_images/378800000409299941/87ccae607fe35081777f49c05b0fbbd2.png" alt="BlaBla"></a>
        </li>
    </ul>
</div>

CSS

.container {
            position: relative;
            padding-top:64px;
            padding-bottom: 64px;
            margin: 0 auto;
            width: 728px;
            border: 1px solid black;
        }

        .thumb-list {
            margin: 0 auto;
            position: relative;
            list-style: none;
        }

        .thumb-list li {
            position: relative;
            display: inline;
            margin: 15px;
}

.thumb-list li a img{

            height: 128px;
            width: 128px;
            border: 20px solid rgba(0, 0, 0, 0.3);
            -moz-border-radius: 50%;
            -webkit-border-radius: 50%;
            border-radius: 50%;



        }

.thumb-list li a img:hover {
            -webkit-animation: toSquare 1s alternate; /* Safari 4+ */
            -moz-animation:    toSquare 1s alternate; /* Fx 5+ */
            -o-animation:      toSquare 1s alternate; /* Opera 12+ */
            animation:         toSquare 1s alternate; /* IE 10+ */
            -webkit-animation-fill-mode: forwards;


        }
        @-webkit-keyframes toSquare {
            0%   {

                -moz-border-radius: 50%;
                -webkit-border-radius: 50%;
                border-radius: 50%;
            }
            100% {

                -moz-border-radius: 30%;
                -webkit-border-radius: 30%;
                border-radius: 30%;


            }
        }