Код:

<ul style="list-style: none;" class="marquee">
<li class="marqueeli"><img src="/images/1.jpg" alt="" ></li>
<li class="marqueeli"><img src="/images/2.jpg" alt="" ></li>
</ul>

Стиль:

<style>
.marquee{width: 100%;display: flex; margin: 0 auto; white-space: nowrap; overflow: hidden; box-sizing: border-box;}
.marqueeli{float:left;display: inline-block;padding-left: 10%;animation: marquee 15s linear infinite;}
@keyframes marquee {0% {transform: translate(0, 0);}100% {transform: translate(-100%, 0);}}
</style>