JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
<span class="marquee">This is a marquee!</span>
</div>

CSS

.wrapper{
    max-width: 400px;
    background: green;
    height: 40px;
    text-align: right;
}

.marquee {
    background: red;
    white-space: nowrap;
    -webkit-animation: rightThenLeft 4s linear;
    margin-right: 10000px;
}

@-webkit-keyframes rightThenLeft {
    0%   {margin-right:100%;}
    50%  {margin-right:0;}
    100% {margin-right:100%;}
}