JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="panel">
    <div class="item">1</div>
    <div class="item">2</div>
    <div class="item">3</div>
    <div class="item">4</div>
    <div class="item">5</div>
    <div class="item">6</div>
    <div class="item">7</div>
    <div class="item">8</div>
    <div class="item">9</div>

    <!-- Something weird happens after this -->
    <div class="item">10</div>
  </div>
</div>

<div>
  Left offset of
  <mark>panel</mark>:
  <span id="log"></span>
</div>

<button onclick="removeLastItem()">
  Remove last item
</button>

CSS

* {
  box-sizing: border-box;
}

.item {
  display: inline-block;
  width: 160px;
  height: 80px;
  outline: 1px solid red;
}

.container {
  -moz-column-width: 320px;
  column-width: 320px;
  -moz-column-fill: auto;
  column-fill: auto;
  max-height: 160px;
  width: 640px;
}

JavaScript

function logOffset() {
  document.getElementById("log").innerText = document.querySelector(".panel").getBoundingClientRect().left;
}

window.removeLastItem = function() {
  var items = document.querySelectorAll(".item");
  if (items.length) {
    items[items.length - 1].remove();
    logOffset();
  }
}

logOffset();