JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
  <div class="element">
    <img src="http://placehold.it/150x150" alt=""/>
  </div>
</div>

CSS

#container {
  white-space:nowrap;
  overflow: hidden;
}

.element {
  display: inline-block;
  vertical-align:top;
}

.element.lastvisible {
  border:5px solid red;
  box-sizing:border-box;
}

JavaScript

var vwidth = $(window).width()
var ewidth = $(".element").width()
var total = vwidth / ewidth
var integer = parseInt(total)

$(".element").eq( integer - 1 ).addClass("lastvisible")